Reviewer: Kerstin Glaus
Editor: Billo Heinzpeter Studer

Initial release: 2016-03-15
Version information:

• Appearance: B
• Last minor update: 2022-10-05

Cite as: »Volstorf, Jenny. 2022. Dicentrachus labrax (Dossier). In: fair-fish database, ed. fair-fish. World Wide Web electronic publication. First published 2016-03-15. Version B | 1.1. https://fair-fish-database.net.«

collapse 

• Unpredictable influence:
  • Observations WILD: individuals stayed on location after escape (➝ D1) 1.
• Competition: no data found yet.
• Disease transmission: no data found yet.
• Interbreeding: no data found yet.

collapse 

• For daily rhythm ➝ 2.
• For migration ➝ 3 4 5 6.
• For schooling, shoaling ➝ 3 2 5 7.

collapse 

• For daily rhythm ➝ 8 9.
• For swimming ➝ 10 11 12 13.
• For social organisation ➝ 14 8 9 15.
• For aggression ➝ 16 15.
• For learning ➝ 14 8 7 9.
• For coping styles ➝ 17 7 9 15.

collapse 

• Observations Mediterranean: harbour of Cap d'Adge, Mediterranean, France 17, Ingril and Prevost lagoons and channel between them, Mediterranean, France 5, Messolonghi-Etoliko lagoon, Mediterranean, Greece 19.
• Observations eastern Atlantic: Ria de Aveiro, western Portuguese coast 20, Mira estuary, Atlantic, western Portuguese coast 20, Mondego estuary, Atlantic, western Portuguese coast 6 20, salt marsh pond, Atlantic, western French coast 2, Tagus estuary, Atlantic, western Portuguese coast 21 20.
• Observations British Isles: English and Welsh coast 22 23, Irish coast 3, northern and southern Devon coast, England 4, Severn estuary and Bristol channel, south west England 24, several harbours and bays on the southern Irish coast 25.

collapse 

• Observations Grey mullet WILD: 0+ JUVENILES: Crenimugil labrosus: southern Irish coast 25, ADULTS: Liza ramada, Liza aurata, and Chelon labrosus: English and Welsh coast 22.
• Observations Sole WILD, 0+ JUVENILES: Solea solea: southern Irish coast 25, Mondego estuary, Atlantic, western Portuguese coast 6.

collapse 

• Plants:
  • WILD: JUVENILES-ADULTS were found with reeds (Phragmites spp.), broad-leaved Potamogeton, wrack (Fucus spp.): Irish coast 3.
  • For substrate and spawning ➝ D2.
• Rocks and stones: no data found yet.
• Sand and mud:
  • WILD: JUVENILES were found over sandy beaches, sand banks but also muddy bottoms: Irish coast 3.
  • WILD: majority of 0+ and 1+ JUVENILES were found over mud and muddy sand: southern Irish coast 25.
• Other substrate: no data found yet.

collapse 

• Observations: 3-4.6 increasing with D. labrax sizes: Messolonghi-Etoliko lagoon, Mediterranean, Greece 19, 3.5±0.5 se 26.

collapse 

• Carnivorous D3. The fishery that provides fish meal and fish oil has two major impacts:
  1. It contributes considerably to overfishing, as it accounts for 1/4 27 or even 1/3 28 of the world catch volume.
  2. It challenges animal welfare, because in the face of 450-1,000 MILLIARD wild fishes caught worldwide each year to be processed into fish meal or fish oil 29, the individual fish gets overlooked and, thus, suffering increases at rearing, live marketing, and slaughtering levels 30.

collapse 

• Food items: carnivorous:
  • Observations WILD, 0+ JUVENILES: mainly crustaceans: southern Irish coast 25, mainly crustaceans (e.g. shrimp Neomysis integer, unidentified Gnathiidae, Sphaeroma sp., Palaemon spp., Crangon crangon, Corophium sp.), fish (Pomatoschistus spp.), polychaeta, bivalve Scrobicularia plana: Tagus estuary, Atlantic, western Portuguese coast 21, mainly Copepoda, Decapoda, further: Polychaeta, Amphipoda, Mollusca: Mondego estuary, Atlantic, western Portuguese coast 6.
  • Observations WILD, JUVENILES-ADULTS: Amphipods (Gammarus sp.), shrimps (Palaemon sp.), crabs (Carcinus sp.), finfish (Atherina boyeri) and mugilids (Mugilidae) fry and juveniles, copepods: Messolonghi-Etoliko lagoon, Mediterranean, Greece 19.
• Food items and habitat: no data found yet.
• Food items and life stages: mainly crustaceans, increasing amount of fish with increasing age:
  • WILD: Irish coast 3:
    FRY: crustaceans (calanoid copepods, gammarids, mysids), polychaete larvae, insects (Diptera),
    1+ JUVENILES: crustaceans (shrimp Crangon, mysids, gammarids, Corophium), further: ragworm Nereis diversicolor, gastropods, small fish,
    1+-4+ JUVENILES: crustaceans (amphipod Corophium volutator, small crab Carcinus, shrimp Crangon, prawn Plaemon serratus, gammarid, isopods), worms (ragworm Nereis diversicolor, lugworm Arenicola, white ragworm Nephtys sp.), small fish,
    ADULTS: crustaceans (shore crab Carcinus, edible crab Cancer, swimming crab Portunus holsatus, hermit crab Pagurus sp., prawn Palaemon serratus, shrimp Crangon, Hippolyte sp., mysids, Idothea balthica and/or linearis), fish (flounder and/or plaice Pleuronectidae, herring fry Clupea harengus, sprat Sprattus sprattus, sand eels Ammodytidae, brill Scophthalamus rhombus, blenny Blennius pholis, butterfish Pholis gunnellus, stickleback Spinachia, sea scorpion Taurulus bubalis), lugworm Arenicola, bivalves, sea anemone.
  • WILD: Messolonghi-Etoliko lagoon, Mediterranean, Greece 19:
    JUVENILES (17-31 mm): small size crustaceans (copepods, nauplii of decapods),
    JUVENILES (32-200 mm): medium size crustaceans (amphipods Gammarus sp., isopods Sphaeromatidae and Idoteidae)m
    ADULTS (201-280 mm): Amphipods (Gammarus sp.), small shrimps (mainly Palaemon sp.) and crabs (Carcinus sp.),
    ADULTS (281-748 mm): small and medium size fish (e.g. Atherina boyeri, Mugilids fry and juveniles).
• Food preference: no data found yet.
• Food partitioning: no data found yet.
• Prey density: no data found yet.
• Prey size selectivity: no data found yet.
• Particle size: no data found yet.

collapse 

• Items found in stomach D3 indicate that JUVENILES probably peck for food or search through sand or mud for burrowing worms.
• WILD: shoals of ADULTS pursued fishes: Irish coast 3.

collapse 

• FARM: in semi-submerged cages at stocking density of 3 kg/m³, individuals swam predominantly at the bottom of the cage out of observation range. When observable, they swam horizontally, towards the bottom, and with frequent turns, resembling random searching for food in the wild 33.

collapse 

• Daily rhythm:
  • WILD: lower number of empty stomachs in 0+ JUVENILES caught 08:00-20:00 h, higher feeding activity during low tide: Tagus estuary, Atlantic, western Portuguese coast 21.
  • WILD: school migration mainly at dusk or dawn: Ingril and Prevost lagoons and channel between them, Mediterranean, France 5.
  • WILD, ADULTS: higher mean nocturnal (789 versus 293 m/h) than diurnal swimming activity of solitary ADULTS in 250 m² earthen pond. Probably to avoid avian predators by day. Inter-individual differences, though: two of seven ADULTS without obvious rhythm. In group of 60 ADULTS, higher diurnal (491 versus 183 m/h) than nocturnal swimming activity. Range of diurnal swimming activity 600-1,200 m/h: salt marsh pond, Atlantic, western French coast 2.
  • LAB, JUVENILES: highest activities at self-feeder at 06:00 h (light onset) and 11:00 h 8.
  • LAB, JUVENILES: highest activities at self-feeder at 08-10:00 h and 19-22:00 h 9.
• Nocturnal activity: ➝ Daily rhythm.
• Phototaxis: no data found yet.

collapse 

• Standard temperature range: 10-27 °C:
  • Observations WILD: <13-21 °C (leave from December on): Severn estuary and Bristol channel, south west England 24, 12-27 °C: Tagus estuary, Atlantic, western Portuguese coast 21, 12-24 °C (leave probably from September on): Ingril and Prevost lagoons and channel between them, Mediterranean, France 5, 10-26 °C (leave from January on): Mondego estuary, Atlantic, western Portuguese coast 6.
• Temperature preference: no data found yet.
• Migration temperature: spring through summer, POST-LARVAE migrate to coastal lagoons or estuaries, autumn through winter, JUVENILES leave to the open sea (➝ D7) probably due to decreasing temperatures:
  • Observations decreasing temperatures WILD, JUVENILES-ADULTS: 24, Ingril and Prevost lagoons and channel between them, Mediterranean, France 5.
  • WILD: JUVENILES-ADULTS left areas with <9 °C in autumn and did not return until temperatures >9 °C: Irish coast 3.
  • WILD: ADULTS migrated north in summer and south in winter probably to stay in water >9 °C: English and Welsh coast 23 34.
• For temperature and...
  ...swimming speed ➝ D8,
  ...spawning ➝ D2.

collapse 

• Lower and upper lethal limits:
  • LAB, LARVAE: lower survival when eggs were reared at 15 than at 20 °C (28% versus 64%) 12.
• Temperature change and stress:
  • LAB, JUVENILES: at 38 ppt, higher plasma cortisol (30 ng/mL versus 10 ng/mL) and higher susceptibility to nodavirus when raised in 17 °C water than in 23 °C water from hatching to six months. Scrubbing for 5 min, three times a day in last three of six months did not influence result. Switching temperature between 17 and 23 °C on alternate days in last three months increased plasma cortisol (155-186 ng/mL versus 7-40 ng/mL) compared to constant temperature (17 °C or 23 °C) for six months or scrubbing in last three months; also increased susceptibility to nodavirus compared to constant temperature 35.

collapse 

• Temperature must exceed: 13-14 °C:
  • FARM, JUVENILES-ADULTS: 13 months old JUVENILES in 7 x 7 x 7 m cage at 2.2 kg/m³ density, increasing to 9.2 kg/m³ as individuals grew to 24 months. At 37.5-38.5 ppt salinity, growth rate increased with increasing water temperature: from -0.3-0.1 at 14-18 °C to 0.4-0.6 at 22-26 °C. No correlation with PHOTOPERIOD 36.
• Temperature must not go beyond: no data found yet.
• Optimal temperature for growth: 18-26 °C:
  • WILD: better growth in years with air temperature 17-19 °C (probably not differing much from water temperature) during summer months than other years with lower temperatures: Irish coast 3.
  • WILD: 0+ individuals made biggest growth spurt in August through October at temperatures 14-21 °C 24.
  • WILD: peak of growth rate of 0+ JUVENILES during July and August with ca 23-26 °C: Tagus estuary, Atlantic, western Portuguese coast 21.
  • LAB, JUVENILES: in 500 L tanks at 38 ppt, higher weight when raised in 23 °C water (22.5 g versus 8.7 g) than in 17 °C water from hatching to 6 months 35.

collapse 

• Observations WILD, JUVENILES: 4.5-12 mg/L: Mondego estuary, Atlantic, western Portuguese coast 6.

collapse 

• Salinity tolerance:
  • Natural distribution in brackish and fresh water as POST-LARVAE and JUVENILES, as JUVENILES and ADULTS in seawater D7 D9.
• Standard salinity range:
  • Observations WILD, JUVENILES: 0-29‰ depending on the river: Irish coast 3, 6-30+‰, 0+ JUVENILES preferably in 17-21‰: southern Irish coast 25, 13-28‰: Tagus estuary, Atlantic, western Portuguese coast 21, 0-35‰: Mondego estuary, Atlantic, western Portuguese coast 6.
• Salinity and migration: migration to the open sea (➝ D7) probably due to decreasing salinity:
  • Observations decreasing salinity WILD, JUVENILES-ADULTS:  Ingril and Prevost lagoons and channel between them, Mediterranean, France 5.

collapse 

• Observations: 37.

collapse 

• Absolute swimming speed:
  • Observations WILD, JUVENILES: when migrating offshore moved at average 1.4 km/day: northern and southern Devon coast, England 4.
  • LAB, JUVENILES: in a respirometer, increasing water velocity in a constant acceleration test from 30 cm/s by 10 cm/s/min until JUVENILES fell back against the retaining grid from exhaustion yielded maximum speed attainable (U cat) of 169.6 cm/s. Transition to burst-and-coast swimming where JUVENILES supplemented thrust with anaerobic muscle contractions at 95.8 cm/s. Maximum speed decreased (136.6, 134.5, 131.5 cm/s) and speed, at which burst-and-coast swimming starts, increased (105.6, 111.2, 110.3 cm/s) in three subsequent trials each 5 min apart. Tail beating frequency increased with increasing water velocity until start of burst-and-coast swimming when it reached a plateau. Constant tail beating amplitude until burst-and-coast swimming, wider afterwards. Inter-individual variation not only in maximum speed and start of burst-and-coast swimming but in oxygen uptake and time to recovery: mean of 3.5 hours until fish oxygen uptake was back at level before test. The higher maximum swimming speed the longer recovery period (and conversely) 13.
  • LAB, JUVENILES-ADULTS: mean absolute critical swimming speed 91-127 cm/s. Positive correlation between total length and absolute critical swimming speed 10.
• Relative swimming speed:
  • LAB, JUVENILES-ADULTS: mean relative critical swimming speed 3.6-4.1 body lengths/s. Negative correlation between total length and relative critical swimming speed 10.
• Swimming speed and temperature:
  • LAB: JUVENILES in groups of 7-10 in 500 L tanks of either 7, 11, 14, 18, 22, 26, or 30 °C were placed after 12-18 days acclimation into respirometer of 60 cm length and 11.5 cm diameter at velocity 10 cm/s. Next day, speed increased at 4 cm/s/min until maximum speed where JUVENILES transitioned to burst-and-glide swimming. Increasing U max with increasing acclimation temperature from 0.7 m/s at 7 °C to 1.1 m/s at 30 °C. No deterioration in swimming efficiency in terms of energy expenditure 11.
  • LAB: JUVENILES kept under 15 or 20 °C from epiboly to 48 or 58 days post fertilisation, then under 18.5 °C for 4-6 weeks. Tested for relative critical swimming speed at either 15, 20, 25, or 28 °C. JUVENILES in experimental groups differed in total length, but no difference in critical swimming speed relative to total length. No difference in relative critical swimming speed at 15 °C between JUVENILES reared under 15 or 20 °C (ca 6.2 total length/s). Higher relative critical swimming speed at 20-28 °C in JUVENILES reared under 15 °C than those reared under 20 °C (20 °C: ca 6.9 versus 6.2 total length/s, 25 °C: ca 9.9 versus 8.5 total length/s, 28 °C: ca 10.8 versus 8.9 total length/s). Result could at least partially be due to higher proportion of red muscle area and higher number of red myofibres in JUVENILES reared under 15 °C than those reared under 20 °C 12.

collapse 

• Standard velocity range:
  • WILD: JUVENILES found in current with velocities 0 to >200 cm/min: southern Irish coast 25.
• Velocity preference: no data found yet.
• Velocity and temperature: no data found yet.

collapse 

• WILD: 76% of JUVENILES-ADULTS recaptured within 16 km around tagging site: northern and southern Devon coast, England 4.
• WILD: in summer, majority of JUVENILES-ADULTS (76% in late 1970s and early 1980s, 55% in 2000-2006) recaptured within 16 km around tagging site 38.
• WILD/FARM: after a planned escape, five of 10 ADULTS stayed within 600-800 m diameter around the release farm during the 60-day-study-period. Not to be excluded that stationary individuals were dead. At least from day 4 after release on, three ADULTS travelled at least 3.5 km away to another farm. Either high site fidelity or high mortalities 1.
• For daily swimming range ➝ D10.

collapse 

• Depth range in the wild: 0.8-73 m:
  • Observations WILD, JUVENILES: observed in very shallow waters but also caught in 3-40 fm (5-73 m): Irish coast 3, highest densities of 0+ JUVENILES in shallow areas of Tagus estuary, Atlantic, western Portuguese coast 21, 2.8 m: harbour of Cap d'Adge, Mediterranean, France 17.
  • Observations WILD, ADULTS: 0.8 m: salt marsh pond, Atlantic, western French coast 2, <1.5 m: Ingril and Prevost lagoons and channel between them, Mediterranean, France 5.
• Depth in cages or tanks: no data found yet.
• Depth preference: no data found yet.
• Depth and daily rhythm: no data found yet.
• Depth and low temperatures: no data found yet.
• Depth and high temperatures: no data found yet.
• Position in habitat and age: no data found yet.
• Depth and light intensity: no data found yet.
• Depth and noise: no data found yet.
• Depth and threat: no data found yet.

collapse 

• ADULTS live and spawn in the open sea:
  • WILD: eggs were found in river mouths or offshore: Irish coast 3.
  • WILD: eggs were found ca 28-65 km off southern English coast in April-June. Never observed in Tamar estuary or off mouths of Devon estuaries, southern England 39.
  • WILD: ADULTS were recaptured in the north in summer and in the south or offshore in winter, typically 400-500 km, up to 800 km from tagging place: English and Welsh coast 34.
• POST-LARVAE migrate inshore to spend JUVENILES stage in estuaries, lagoons, or boardering rivers:
  • WILD, POST-LARVAE-JUVENILES: with decreasing distance to southern English coast, increasing density (➝ D11) and increasing size: ca 4.3-8.3 mm: >19 km offshore, ca 5.5-9.3 mm: <19 km offshore. POST-LARVAE were found in Tamar estuary, southern England, in May-August. Decreasing size with increasing distance to estuary mouth: 33 mm: <28 km upstream, <60 mm JUVENILES: <21 km upstream, >10 cm JUVENILES: 40% at 19 km, 70% at 8.5 km from mouth 39.
  • WILD: JUVENILES (ca 10 cm, 1 year) migrated to estuaries where they resided until 2-3 years old: northern and southern Devon coast, England 4.
  • WILD: JUVENILES were recaptured in estuaries in summer and winter: English and Welsh coast 34.
  • WILD: 0+ JUVENILES first appeared in Tagus estuary, Atlantic, western Portuguese coast in May, highest density in June 21.
  • WILD: 0+ JUVENILES entered Mondego estuary, Atlantic, western Portuguese coast, in June 6.
  • WILD: 0+ JUVENILES entered nursey grounds on Portuguese west coast in May-July: Ria de Aveiro, Mondego estuary, Tagus estuary, Mira estuary 20.
  • WILD, JUVENILES-ADULTS: observed in estuaries, creeks, bays, river mouths, streams, headlands, rivers up to 30 miles upstream: Irish coast 3.
  • WILD, JUVENILES-ADULTS: peak abundance of age classes 0+ to 5+ but mostly 0+ individuals in Severn estuary, south west England, during September to December 24.
  • Observations lagoon abundance WILD, JUVENILES: Ingril and Prevost lagoons and channel between them, Mediterranean, France 5.

• JUVENILES migrate offshore in winter (➝ D12):
  • WILD: JUVENILES left river mouths, inshore shallows with beginning of winter: Irish coast 3.
  • WILD: from ca 3 years old on, in winter, JUVENILES migrated offshore: northern and southern Devon coast, England 4.
  • WILD: migrated from lagoons in Mediterranean, France, to the sea in September 5.
  • WILD: from end of second year on, JUVENILES migrated from Mondego estuary, Atlantic, western Portuguese coast to the sea from January on 6.

collapse 

• Observations time from fertilisation until hatching WILD: about 4 days: Irish coast 3.
• Observations size WILD: 1.2-1.4 mm diameter: Irish coast 3.
• Observations weight: no data found yet.

collapse 

• Observations yolk sac absorption: no data found yet.
• Observations TOTAL LENGTH WILD: ca 4 mm after hatching: Irish coast 3.
• Observations TOTAL LENGTH LAB: inflation of swim bladder 6-9 days post hatching at 5.5-6 mm 12.
• Observations weight: no data found yet.

collapse 

• Observations age at beginning of exogenous feeding LAB: day 9 17.
• Observations age, TOTAL LENGTH, and weight WILD: 2.5-3.9 cm fork length (ca 2.7-4.1 cm TOTAL LENGTH), scale cover complete at ca 3.7 cm fork length (ca 3.9 cm TOTAL LENGTH): Irish coast 3, age 0+: 30-65 mm, 4.5 g at end of first year: Severn estuary and Bristol channel, south west England 24, 0+: 35-90 mm: southern Irish coast 25, 0+: 50.6 mm: Tagus estuary, Atlantic, western Portuguese coast 21, 0+: 111 mm at end of first year: Mondego estuary, Atlantic, western Portuguese coast 6, 0+: 48-90 mm when entering nursery grounds: Atlantic, western Portuguese coast 20.
• Observations age and weight FARM: 65-95 days post hatching: 0.3-1.5 g 40, 115 days post hatching: 3-5 g 40.
• Observations age and weight LAB: 87 days post hatching: 0.5 g, 115 days: 1.6 g, 129 days: 2.6 g, 180 days: 8.5 g 15.
• FARM: at 40-41 ppt and 21.5 °C in winter, 23.5 °C in summer, morphological sex determination at around 4 months. At 8-10 months, average 14-17 cm, gonads macroscopically discernable. Gonad to body ratios 3-6 times higher in females than males 40.

collapse 

• Observations age, TOTAL LENGTH, and weight WILD: age 1+: 10.5-13.9 cm fork length (ca 11-15 cm TOTAL LENGTH): Irish coast 3, age 1+: 60-160 mm, ca. 38 g at end of second year, age 2+: 120-210 mm, ca. 121 g at end of third year: Severn estuary and Bristol channel, south west England 24, 0+: 75 mm, average back-calculated 64-146 mm, 1+: 144-195 mm, average back-calculated 143-223 mm, 2+: 260 mm and 209 g, average back-calculated 213-291 mm, 3+: 282-335 mm and 272-456 g, average back-calculated 295-354 mm: southern Irish coast 25, 133-167 days: harbour of Cap d’Agde, Mediterranean, France 17, 140 mm, 460 days: harbour of Cap d’Agde, Mediterranean, France 7.
• Observations age, TOTAL LENGTH, and weight FARM: 8 months, males and females: 14.3 cm, 51.3-52.6 g 40, 13 months, average 153 g 36, 105-248 g 11, 30 months, 405 g, 31.2 cm 41, 31.9 cm, 350 g 42.
• Observations age and weight LAB: 8-32 g 35, 139.8 g 43, 231-261 g 44, 40.3 g 8, 71.5-136.0 g, 300-480 g 45, 630 days: 639.4 g 15.
• Sexual maturity: males: 7 years, 33-34 cm, females: 5+ years, 38-42 cm:
  • Observations age and TOTAL LENGTH of males WILD: from 31.7 cm fork length (ca 33.7 cm TOTAL LENGTH) and 7 years on: Irish coast 3, males from 33 cm on: English and Welsh coast 23.
  • Observations age and TOTAL LENGTH of females WILD: 35.5 cm fork length (ca 37.8 cm TOTAL LENGTH) and 5+ years: Irish coast 3, females from 42 cm on: English and Welsh coast 23.

collapse 

• Observations age, TOTAL LENGTH, and weigth WILD: maximum 24 years, heaviest male: 19+ years and 68.6 cm fork length (ca 73 cm TOTAL LENGTH) and 4.1 kg, heaviest female: 19+ years and 82.5 cm fork length (ca 87.8 cm TOTAL LENGTH) and 6.9 kg: Irish coast 3, 72 cm: Devon coast, England 4, age 3+: 180-260 mm, 280 g, 4+: 230-300 mm and ca. 441 g, 5+: 290 mm: Severn estuary and Bristol channel, south west England 24, maximum 20+ years, maximum 82 cm: English and Welsh coast 34, 5+: 350-450 mm, mean 635 g, 6+: 360-470 mm, mean 830 g, 7+: 410-530 mm, mean 999 g, 8+: 430-490 mm, mean 1,096 g, 9+: 430-510 mm, 1,056 g, 10+: 470 mm, mean 1,115 g, 11+: 480-520 mm, mean 1,251 g, 12+: 500-600 mm, mean 1,713 g, 13+: 590 mm, mean 2,191 g, 15+: 640 mm, mean 2,791 g, 16+: 600 mm, mean 2,303 g, 17+: 660 mm, mean 3,058 g: English and Welsh coast 22, 18+ years (back-calculated from size), English and Welsh coast 22, southern Irish coast 25, 3+: 230-580 g: salt marsh pond, Atlantic, western French coast 2, 4+: 325-337 mm and 403-506 g, average back-calculated 368-413 mm, 5+: average back-calculated 407-430 mm, 6+: average back-calculated 452-465 mm, 7+: average back-calculated 488-494, 9+: average back-calculated 528 mm: southern Irish coast 25, >40 cm 38.
• Observations age and weight FARM: 24 months, 390 g 36.

collapse 

• Sex and temperature manipulation: no data found yet.
• Sex and hormone treatment:
  • FARM: treatment with 10 mg/kg dry food of the androgen 17-alpha-methyltestosterone increased portion of male FRY compared to control group (100% versus 85.3%) regardless of age at beginning of treatment (65 or 95 days post-hatching) and regardless of duration of treatment (75 or 100 days). Slightly lower male proportion (91.5%) and 8.5% of an intersex when beginning treatment at 115 days 40.
  • FARM: treatment with 125 mg/kg dry food of the estrogen estradiol increased portion of female FRY compared to control group (100% versus 17.3%) regardless of age at beginning of treatment (65 or 95 days) and regardless of duration of treatment (75 or 100 days). Lower female proportion (85%) and 15% an intersex when beginning treatment at 115 days 40.
• Sex and genetic manipulation: no data found yet.
• Sex and other manipulation: no data found yet.

collapse 

• Observations WILD: 1:2: Irish coast 3.

collapse 

• Growth:
  • FARM: in floating cages, growth halted 4-5 months per year 46.
• Natural growth rate:
  • WILD: 7-9 cm fork length (ca 7.4-9.6 cm TOTAL LENGTH) in first two years, 6-7 cm fork length (ca 6.4-7.4 cm TOTAL LENGTH) in years 3-4, 4-5 cm fork length (ca 4.3-5.3 cm TOTAL LENGTH) in years 5-7, thereafter 2-3 cm fork length (ca 2.1-3.2 cm TOTAL LENGTH): Irish coast 3.
  • WILD, 0+ JUVENILES: average 0.7 mm/d, peak of 1.5 mm/d in July and August: Tagus estuary, Atlantic, western Portuguese coast 21.
  • WILD, 0+ JUVENILES: 0.5-0.6 mm/d in nursery grounds in Atlantic on western Portuguese coast, increasing with decreasing latitude 20.

collapse 

• Observations bimodal pattern WILD: males did not grow as fast as females and were not as long-lived: Irish coast 3.
• Observations bimodal pattern FARM: 10 months: females 15.3-20.2 cm and 47.4-106 g, males 13.7-19.8 cm and 34.1-97.5 g, 24 months: females 31-38 cm and 310-552.8 g, males 30.2-34.6 cm and 322-453.3 g 40.
• Beginning of noticeable size difference:
  • FARM: in tanks of different sizes at 40-41 ppt and 21.5 °C in winter, 23.5 °C in summer, females grew longer and heavier than males, the difference noticeable from 10 months on 40.

collapse 

• LAB: non-graded JUVENILES in 400 L tanks with self-feeder. Grading at day 27: three tanks with high variation in weight (20%, 21.1-65.1 g) maintaining social structure, three tanks with low variation (10%, 33.7-49.7 g) disrupting social structure. At 54 days since grading, no difference in body weight, body length, specific growth rate (0.7-0.9) 8.

collapse 

• Nest building and substrate: no data found yet.
• Nest building and water velocity: no data found yet.
• Nest building and water depth: no data found yet.
• Nest building: no data found yet.
• For breeding type ➝ D15.

collapse 

• Spawning substrate: none:
  • WILD: eggs were caught at surface, not attached to substrate: Irish coast 3.
• Spawning season: winter-spring:
  • Observations WILD: March-June with peak in May, eggs were caught at sea surface temperatures 10-15 °C, mostly 10-12 °C: Irish coast 3, May-June: Severn estuary, south west England 24, April-June: off southern English coast 39, January-June with peak in April: English and Welsh coast 23, winter-spring season: Mondego estuary, Atlantic, western Portuguese coast 6, December-April: Atlantic, western Portuguese coast, earlier the lower the latitude, at <13-14 °C sea surface temperature on west coast, increasing with decreasing latitude 20.
• Spawning (day)time: no data found yet.
• Spawning temperature: ➝ Spawning season.
• Spawning salinity:
  • Observations WILD: in river mouths or offshore at 14-35 ppt salinity: Irish coast 3.
• Spawning and water velocity: no data found yet.
• Spawning depth: no data found yet.
• Spawning density: no data found yet.

collapse 

• Male:female ratio resulting in spawning:
  • FARM, ADULTS: group spawning: 1-2 females plus 2-3 males in 600 L spawning tanks. Single-pair crossing via stripping 40.
• Composition of broodstock:
  • FARM, ADULTS: higher variation (69.3-98.1 versus 44.2-52.0%) and higher mean proportion of males (86.5% versus 50.8%) in progenies from group spawnings compared to single-pair crossings. Proportions remained the same with increasing age 40.

collapse 

• Spawning sequence: no data found yet.
• Spawning duration:
  • WILD, ADULTS: females probably do not shed eggs altogether in short amount of time but in batches over longer time: Irish coast 3.

collapse 

• Number of batches: probably several D16.
• Fecundity per batch:
  • Observations absolute fecundity: no data found yet.
  • Observations relative fecundity WILD, ADULTS: 293,000-358,000 eggs/kg body weight: Irish coast 3.

collapse 

• Breeding type: sea spawner:
  • Observations: ➝ D7.
• Nursery grounds:
  • Lagoons are considered nursery grounds: the shallow brackish water excludes many predators, offers higher temperatures D17 D13 and lower salinities than the open sea, as well as abundant prey.

collapse 

• Hearing type:
  • LAB, FRY: hearing GENERALIST 47.
• Hearing spectrum: no data found yet.

collapse 

• WILD: school of 560 JUVENILES was observed at 280 cm depth: harbour of Cap d’Agde, Mediterranean, France 7.
• WILD: shoal of 0+ to 4+ JUVENILES in a creek, shoals of ADULTS offshore (➝ D18), but JUVENILES more often in schools, ADULTS more often solitary: Irish coast 3.
• WILD, JUVENILES-ADULTS: in schools with surface area of probably median 1-2 m², maybe even up to 14 m² based on sonar surveys and catch per unit of effort. School shape ratio (lengthwise/crosswise) probably <1: channel between Ingril and Prevost lagoons, Mediterranean, France 5.
• WILD: shoal of 60 ADULTS adapted to common daily rhythm (➝ D10): salt marsh pond, Atlantic, western French coast 2.
• For aggregation type and cooperation ➝ D18.

collapse 

• Observations WILD, 0+ JUVENILES: mean 0.4-1.0 IND/1,000 m² in some areas, mean 4.5 and maximum 81.8 IND/1,000 m² in other areas of Tagus estuary, Atlantic, western Portuguese coast 21.

collapse 

• FARM: in a raceway, mean fin erosion index of JUVENILES and ADULTS in stocking densities of 42-79 kg/m³ ranged at 1.1-1.3, where level 1 indicates change in total fin area <10% and micro-splits on front tips or one clean split of >1/2 fin length. Highest erosion at posterior dorsal and caudal fins. Higher frequency of fin ray deformity (36-74% versus 26-40%) and necrosis (34-82% versus 30-48%) in ADULTS than JUVENILES where the production cycles were 97 versus 54 weeks 46.
• FARM: in floating cages, mean fin erosion index of JUVENILES and ADULTS in stocking densities of 8.4-23.7 kg/m³ ranged at 0.9-1.2. Highest erosion at pectoral and posterior dorsal and caudal fins. Higher frequency of ray deformity (20% versus 0-10%) in ADULTS than JUVENILES where the production cycles were 40 versus 10-30 months 46.
• LAB: JUVENILES in circular tanks of 5 m³ at densities 15, 30, or 45 kg/m³. After six weeks, no difference in cortisol and glucose levels, but tendency of decrease in cortisol levels compared to two weeks since beginning of experiment (six weeks: 16.5-20.7 ng/mL versus two weeks: 23.7-27.3 ng/mL) and tendency of increase in glucose levels (six weeks: 106.3-113.7 mg/dL versus two weeks: 82.1-90.8 mg/dL) 43.
• LAB, JUVENILES: in 0.5 m³ tank, increasing fin erosion with increasing stocking density after four months: at final stocking density 20 kg/m³, mean erosion index 0.06-0.15 regardless of oxygen level (102% or 80%), where level 0 means "perfect fin, all fins with extremities intact". At final stocking density 120 kg/m³, higher oxygen level increased fin erosion: with 53% oxygen, mean erosion level 1.0. With 106% oxygen, mean erosion index 1.5, where level 2 indicates change in total fin area <20% and <5 minor "V form" fin splits of <1/3 fin length or one clean split of >1/3 fin length. Highest erosion at posterior dorsal and caudal fins 46.
• LAB: JUVENILES, acclimated to 70 kg/m³, were transferred to 1 m³ tanks of recirculating aquaculture system at densities 10, 40, or 100 kg/m³. After 63 days, no difference in survival (99%). Half of few mortalities (1%) by individuals jumping out of the tank. After 21 and 63 days, no difference in cortisol levels (ca 38-51 ng/mL). After 63 days, no difference in glucose levels (77-84 mg/L). After 63 days, inoculation with nodavirus. After 25 days, no difference in morbidity (65-72%) 50.
• LAB: JUVENILES in 200 L chambers at either 5.5 or 36.0 kg/m³ stocking density and either fed at maintenance, medium, or satiation level. After 70 days (now under densities of ca 10 and 60 kg/m³), no difference in survival (99%) between stocking densities. No difference in glucose levels between stocking densities (ca 5-6 mmol/L), but tendency of higher cortisol levels under high than low density (ca 175-280 ng/mL versus 80-130 ng/mL) 16.

collapse 

• Inverse relation:
  • FARM: in a raceway, JUVENILES had higher weight (427 versus 375 g) at stocking density of 48 kg/m³ than 58 kg/m³; 42 kg/m³ in between (401 g). ADULTS had higher weight (927 versus 853-854 g) at stocking density of 49 kg/m³ than 62 or 79 kg/m³ 46.
  • FARM: in floating cages 70-90 m from bay mouth, JUVENILES had higher weight after 30 months (474 g versus 408 g) at stocking density 11.3 kg/m³ than 15.7 kg/m³ 46.
  • LAB: JUVENILES in circular tanks of 5 m³ at densities 15, 30, or 45 kg/m³. After six weeks, tendency of higher weight under 15 than under 30 kg/m³ (158.1 versus 144.0 g); 45 kg/m³ in between (153.6 g), but overall low growth rate points to issue with experimental setup and represents inconclusive data 43.
  • LAB: JUVENILES in a 0.5 m³ square tank grew better (305.2-330.4 g versus 234.0-244.5 g) under a stocking density that increased during four months to 20 kg/m³ than to 120 kg/m³ 46.
  • LAB: JUVENILES, acclimated to 70 kg/m3, were transferred to 1 m³ tanks of recirculating aquaculture system at densities 10, 40, 70, or 100 kg/m³. Higher feed intake under 10, 40, and 70 kg/m³ than under 100 kg/m³ (ca 1.4% of biomass/d versus ca 1.3%). No difference in FOOD CONVERSION RATIO (1.8-2.1). Higher specific growth rate under 10, 40, and 70 kg/m³ than under 100 kg/m³ (ca 0.8%/day versus 0.7%/day) 50.
• No relation:
  • LAB: JUVENILES in 200 L chambers at either 5.5 or 36.0 kg/m³ stocking density and either fed at maintenance, medium, or satiation level. After 70 days (now under densities of ca 10 and 60 kg/m³), no difference in growth between stocking densities but between feeding regimes with higher weight gain under satiation feeding than under maintenance feeding (0.69-0.83 g/IND/d versus 0.01-0.03 g/IND/d); medium in between (0.30-0.32 g/IND/d) 16.
• Direct relation:
  • FARM: in floating cages >100 m from mouth of a Mediterranean bay, JUVENILES had higher weight after 18 months (267 g versus 159 g) at stocking density 16.4 kg/m³ than 8.4 kg/m³ 46.

collapse 

• Hierarchy and group size:
  • LAB: two similar-sized JUVENILES (day 137) in 42.3 x 26.5 x 15 cm 8.4 L aquaria. In one of 12 pairs, one of JUVENILES became dominant over the other after 10.1 min 15.
• Establishing hierarchy: no data found yet.
• Producers and scroungers: in habitat with self-feeder, few individuals trigger majority of feed:
  • LAB: JUVENILES in 1 m³ tanks with self-feeder at density 15 kg/m³. During 42 days, 40-60% triggered <4% (zero-trigger) 34-54% triggered 4-15% (low-trigger), 6-10% triggered >15% (high-trigger). 3-5 individuals triggered 77-83%. No difference in specific growth rates (-0.003-0.22).
    During 68 days in second experiment, 31-45% triggered <4% (zero-trigger), 47-61% triggered 4-15% (low-trigger), 8-10% triggered >15% (high-trigger). 4-5 individuals triggered 80-84%. No difference in specific growth rates (0.13-0.25). Combining data of both experiments: higher 5-HIAA levels in zero- and low-trigger compared to high-trigger JUVENILES in telencephalon (5.6-6.9 versus 4.2 10^-3 ng/g), cerebellum (4.2-4.5 versus 3.2 10^-3 ng/g), and diencephalon (2.1-2.4 versus 1.6 10^-3 ng/g) indicating higher brain serotonergic activity and thus higher stress in zero- and low-trigger JUVENILES 14.
  • LAB: non-graded JUVENILES in 400 L tanks with self-feeder. Grading at day 27: three tanks with high variation in weight (20%, 21.1-65.1 g) maintaining social structure, three tanks with low variation (10%, 33.7-49.7 g) disrupting social structure. At 54 days since grading, no difference in number of JUVENILES triggering <2% (zero-trigger), <15% (low-trigger), and >15% (high-trigger): 72.9-84.7% zero-trigger, 13.6-27.1% low-trigger, 0-1.9% high-trigger. Two or three individuals triggered about 35% of feed. No difference in specific growth rate (0.7-0.9) 8.
  • LAB, JUVENILES: no dominance-subordination structure but producers and scroungers: in tanks with self-feeder, 67.7-78% triggered <2% (zero-trigger), 16-27.4% triggered 2-8% (low-trigger), 3.7-6.0% triggered >8% (high-trigger) – that means two or three individuals triggered about 45% of pellets. No difference in growth rates and similar sex ratio in trigger categories. High-trigger individuals rather shy, zero- and low-triggers rather bold (for more details ➝ D5) 9.

collapse 

• WILD: ADULTS shoaled while pursuing Herring fry or Sprats (clupeoids): Irish coast 3.

collapse 

• LAB: no aggression recorded among JUVENILES in densities of 10, 40, 70, and 100 kg/m³ 50.

collapse 

• Size-matched pairs:
  • LAB: no injuries and very low mortality among ca 100 x 40 g JUVENILES in 400 L tanks 8.
  • LAB: in one of 12 pairs of similar-sized JUVENILES, the dominant individual chased the subordinate one 15.
• Non-matched pairs:
  • LAB: no agonistic behaviour recorded among ca 50 x 290 g JUVENILES in 1 m³ tanks with self-feeder after two weeks adjustment 14.
  • LAB: JUVENILES at 5.5 kg/m³ stocking density that were manually fed, bit and chased each other 16.
  • LAB: no injuries and very low mortality among ca 100 x 40 g JUVENILES in 400 L tanks 8.

collapse 

• LAB: no competition for triggering area access among ca 50 x 290 g JUVENILES in 1 m³ tanks with self-feeder after two weeks adjustment 14.

collapse 

• Managing self-feeder:
  • LAB: JUVENILES learned how to manage a self-feeder (➝ D4) 14 8 9.
• Object-reward association:
  • LAB: domesticated and wild-caught JUVENILES in a maze. Neither group associated 2-D object with reward (unknown congener), but small sample size and inter-individual differences 7.

collapse 

• Coping styles and feed-triggering:
  • LAB, JUVENILES:
    a) first behavioural test: large inter-individual differences in escaping behaviour when hand-placed in an emerged fixed net. Individuals immediately trying to escape tended to perform a high number of escape attempts (and conversely). Individuals trying to escape longer tended to perform more escape attempts (and conversely) and start those attempts earlier (and conversely).
    b) second behavioural test: large inter-individual differences in staying in secure shelter or swimming in risky open field. Individuals staying shortly in the shelter tended to spend more time in the risky open field and more secure border zone, travel longer distances, and stay at a larger mean distance from the shelter (and conversely).
    c) connection between tests: individuals immediately trying to escape in the first test tended to emerge from the shelter in the second test sooner (and conversely). Individuals with many escape attempts tended to spend less time in the secure shelter (and conversely). Individuals with a high trigger rate at a self-feeder (➝ D4) tended to emerge from the shelter later, stay in the shelter longer, return to the shelter more often, travel a smaller mean distance from the shelter, and spend less time in the risky open field (and conversely), indicating boldness in low- and zero-trigger individuals and shyness in high-trigger individuals. For more correlations ➝ 9.
• Escape attempts from net and age: negative relation:
  • LAB: single JUVENILES in net out of water. During three min, time until escape attempts increased from session 1 at day 557 (3.4 s versus 73.9 s) to session 3 at day 758; session 2 at day 739 in between. Number of escape attempts (37.1 versus 15.5 versus 4.4) and escape duration (33.0 versus 10.2 versus 4.2 s) decreased 15.
• Hypoxia escape and age: no effect:
  • LAB: group of JUVENILES in circular 70 L tank (48 cm height, 49.5 cm diameter) connected to similar tank by acrylic pipe (diameter 11 cm, length 30 cm, at 23 cm from bottom). When decreasing oxygen in base tank from 90% to 8% in 1 h, no difference in O2 level at first passage in session 1 at day 457 and session 2 at day 502 (21.9-30.6%). No difference in number of returns to hypoxic tank (1.3-5.2) and in time to first passage (38.7 versus 43.2 min). Large variability, though 15.
• Boldness and domestication:
  No effect:
  • LAB: domesticated and wild-caught JUVENILES reacted similarly (in a between-subject design) to a plastic tube falling into the compartment the individuals were placed in: until age 91 days, 75-90% of domesticated JUVENILES reacted and 62-94% of wild-caught JUVENILES. From age 98 days on until 125 days (end of observation period), decreasing reactivity (44-59% domesticated, 44-65% wild-caught JUVENILES). No difference, too, in total distance travelled but effect of stimulus: mean 4,732 mm in domesticated versus 4,713 mm in wild-caught JUVENILES before administration of stimulus, 3,390 and 3,567 mm in domesticated JUVENILES 5 and 10 min after the stimulus versus 3,341 and 3,389 mm in wild-caught JUVENILES. Also no difference in immobility but effect of age: lower immobility before and 10 minutes after the stimulus at age 125 days than all previous ages; higher immobility 5 minutes after the stimulus at 111 days than all other ages 17.
  • LAB, JUVENILES: no difference between domesticated and wild-caught JUVENILES in the time spent in zones of a maze, but domesticated JUVENILES covered longer distance (629.9 versus 285.4 mm) at higher velocity (0.07 versus 0.03 body lengths/s) 7.
  Effect:
  • LAB, JUVENILES: higher angular velocity before and after administration of stimulus of wild-caught versus domesticated JUVENILES from age 63 to 98. Also higher distance from stimulus in wild-caught than domesticated JUVENILES 17.

^{In the structure of menu item 16 and the definition of "SHYNESS-BOLDNESS", we follow 51.}

collapse 

• Feeding recovery in novel environment and age: negative relation:
  • LAB: pair of similar-sized JUVENILES in aquarium changing in size as JUVENILES grew from 21 x 27 x 15 cm 8.5 L in session 1 to 60 x 25 x 35 52.5 L in session 3, separated by opaque PVC plate. Feeding recovery decreased from session 1 at day 129 to session 3 at day 548. Feeding latency increased from session 1 to session 3 (2.2 days versus 6.7 days). Large variability, though 15.
• Exploration in T maze and age: positive relation:
  • LAB: single JUVENILES in T maze of 100 x 20 x 15 cm. During 15 min, time spent in safe zone at end of one arm with cover decreased from session 1 at day 150 (259.7 s versus 119.2 s) to session 2 at day 311. Time spent in risky open zone (17.6 s versus 676.2 s) and distance travelled increased (82.9 s versus 244.9 s). Large variability, though 15.
• Risk taking and age: positive relation:
  • LAB: group of JUVENILES in 400 L tank divided into two thirds safe zone with cover, one third risky open zone by opaque plate with 12 cm diameter opening. During 24 h, time to first passage to the risky zone decreased from session 1 at day 187 (568.7 min versus 63.6-96.0 min) to sessions 15 and 30 days later. Number of returns increased (86.5 versus 268.2-309.0). Large variability, though 15.

^{In the structure of menu item 16 and the definition of "EXPLORATION-AVOIDANCE", we follow 51.}

collapse 

• For aggressiveness and...
  ...stocking density ➝ D19,
  ...size-grading ➝ D20.

^{In the structure of menu item 16 and the definition of "AGGRESSIVENESS", we follow 51.}

collapse 

• LAB: JUVENILES confined in 0.1 m³ tanks, at densities of either 10 or 60 kg/m³, both suspended in and connected to 400 m³ tank.
  a) Cortisol: after 3 h confinement, higher cortisol levels under both densities compared to control group at 30 kg/m³ (427-519 ng/mL versus 10 ng/mL). After 48 h confinement, higher cortisol levels compared to control group with higher level under 60 kg/m³ than 10 kg/m³ density (ca 220 ng/mL versus 107 ng/mL).
  b) Glucose: after 3 h confinement, higher glucose levels under both densities compared to control group (136-215 mg/dL versus 86 mg/dL). After 48 h confinement, higher glucose levels under 60 kg/m³ than 10 kg/m³ (ca 310 mg/dL versus 167 mg/dL).
  c) Lysis: after 3 h and 48 h confinement, lower cytotoxicity under 60 kg/m³ compared to 10 kg/m³ and control group (3h: ca 1% versus ca 9-10% of lysis, 48 h: ca 1% versus ca 5%-10% of lysis) 52.
• LAB: JUVENILES in 200 L chambers at either 10 or 60 kg/m³ stocking density for 70 days (for summary of study ➝ D14) were transferred to submerged net for 1 hour. Higher glucose levels under both stocking densities compared to unstressed group (ca 8-13 mmol/L versus 5-6 mmol/L). Higher cortisol levels compared to unstressed group with tendency of higher levels under high than low density (ca 510-790 ng/mL versus 300-700 ng/mL versus 80-280 ng/mL in unstressed group) 16.

collapse 

• LAB: JUVENILES in circular tanks of 5 m³ at densities 15, 30, or 45 kg/m³ subjected to crowding at 100 kg/m³ by draining water for 15 min. At measurement 1 h post stress, increased cortisol levels compared to before stress, higher under 45 kg/m³ than under 15 or 30 kg/m³ (ca 89 ng/mL versus 75-79 ng/mL; ca 17-21 ng/mL pre stress). At second measurement 6 h post stress, still elevated compared to before stress (ca 37-42 ng/mL versus ca 17-21 ng/mL). Back to pre-stress levels at third measurement at 24 h post stress. At 1 h post stress, increased glucose levels compared to before stress, higher under 15 kg/m³ than under 45 kg/m³ (ca 188 mg/dL versus 140 mg/dL; ca 106-114 mg/dL pre stress), 30 kg/m³ in between (ca 165 mg/dL). At 6 h post stress, higher glucose under 15 kg/m³ than under 30 or 45 kg/m³ (ca 195 mg/dL versus 110-130 mg/dL). Back to pre-stress levels at third measurement 24 h post stress 43.
• LAB: individual JUVENILES in 10 m³ tanks at density 10 kg/m³ subjected to crowding by reducing water volume to 2 m³ for 10 min, chasing with net for 3 min, air exposure for 1-2 min:
  a) Cortisol in plasma: in small individuals (99.5 g), increasing cortisol levels with peak (ca 400 ng/mL) at 1 h after stress, thereafter decreasing. At increased stress (60 min confinement versus 10 min, three times 3 min chasing versus one time), increasing cortisol levels with peak (553.8 ng/mL) at 2 h after stress (no further measurement time). In large individuals (366.3 g), increasing cortisol levels with peak (ca 350 ng/mL) at 0.5 h after stress, thereafter decreasing; dito at increased stress.
  b) Glucose in plasma: higher plasma glucose concentration in larger than smaller individuals (10.0 mmol/L versus 5.4 mmol/L); no effect of increased stress. In smaller individuals, no effect of stress on glucose; in larger individuals, increasing concentrations with peak at 1 h after stress.
  c) Lactate in plasma: increasing lactate levels with peak at 0.5 and 1 h after stress in both small and large individuals but higher in large individuals (average 14.1 mmol/L versus 7.2 mmol/L). In large individuals, even higher increase at increased stress (average 17.8 mmol/L) 45.

collapse 

• Cage submergence:
  • FARM, JUVENILES: no difference in growth of individuals in surface and submerged cages (diameter 16 m, depth 10 m, submerged 5 m below the surface), but higher cortisol levels in surface versus submerged individuals (594.1-857.7 ng/mL versus 228.0-403.1 ng/mL), higher haematocrit (35.2-39.8% versus 29.8-30.6%), and higher total protein values (3.5-4.4 g/dL versus 2.5-3.4 g/dL) indicating stress in surface individuals. Positive effect of submergence on immune system on selected dates during the observation period 53.
• Diel changes in plasma cortisol:
  • LAB: individual JUVENILES in 62.8 L net cages in 500 L polyester tanks with aerated seawater (December), sampled every 4 h by lifting net cage into bucket with 0.05 mL/L clove oil. Highest average plasma cortisol level at 18:00 h (79.1 ng/mL), light offset, lowest at 22:00 h (ca 20 ng/mL). Largest variation in cortisol levels at 06:00 h (12.2-302.2 ng/mL), light onset. Support for nocturnal predatory behaviour during winter 45.

collapse 

• Stunning rules: to minimise pain reactions and enhance welfare before slaughter:
  1. induce insensibility as fast as possible,
  2. prevent recovery from stunning,
  3. monitor effectiveness (observations, neurophysiological measurements) 54.

collapse 

• Time to loss of vital signs:
  a) electrical stunning: LAB, JUVENILES: 10 s 44,
  b) CO2 narcosis: LAB, JUVENILES: 16 min 42,
  c) ice asphyxia: FARM, JUVENILES: 20-45 min at 1.4 °C 41; LAB, JUVENILES: 34 min at 2-4 °C 42,
  d) air asphyxia: FARM, JUVENILES: 35-70 min 41; LAB, JUVENILES: 128 min 42.
• Electrical stunning:
  • LAB: in 48 x 17 x 50 cm plexiglass box:
    Experiment 1: JUVENILES restrained with clamp in lower jaw and plastic tie-ribs around body. Head-to-tail stunning of 50 Hz for 1 s in seawater. 8 s tonic phase with tense muscles, 31 s clonic phase with uncontrollably contracting muscles, 11 s exhaustion with flaccid muscles. Seven of 19 JUVENILES did not display muscle tension phases and did not recover. In four of 12 JUVENILES, response to needle scratches 30 s after stunning.
    Experiment 2: see Experiment 1 but non-restrained. During and after 1 s stun, tonic phase. 5 s clonic phase in one of 10 JUVENILES. Swimming movements after 13 s. During and after 10 s stun, tonic phase. Clonic phase in one of 10 JUVENILES. Swimming movements in eight of 10 JUVENILES after 79 s.
    Experiment 3: see Experiment 1 but 10 s stun, 18 s later killed by chilling in ice water for 15 min. Isoelectric line on EEG and no recovery in 10 of 10 JUVENILES.
    Experiment 4: head-to-tail stunning of 133 Hz pulsed square wave alternating current for 1 s in seawater. 6 s tonic/clonic phase, 13 s exhaustion phase with flaccid muscles. In 13 of 20 JUVENILES response to needle scratches 30 s after stunning.
    Experiment 5: method of Experiment 3 in farm context. Similar yield and colour but slightly lower pH values compared to pure live chilling for 40 min in tank with seawater and flake ice (1.5 °C). Vigorous movement after start of live chilling.
    Experiment 6: method of Experiment 4 with 20 s stun on boat. Similar pH values, colour, and yield compared to pure live chilling 44.

collapse 

• FARM: JUVENILES in 330 m³ tanks at 30 kg/m³ either crowded at >70 kg/m³ or uncrowded before slaughter by air asphyxiation (8.0 °C) or ice asphyxiation (1.4 °C). Longer time until no opercular reflex and no branchial movement for crowded than uncrowded JUVENILES (45-70 min versus 20-35 min) probably due to high activity and vigorous movement before unconsciousness. Longer struggle time under air than ice asphyxia (35-70 min versus 20-45 min). Earlier onset of pH decrease in crowded compared to uncrowded JUVENILES (at first measurement after death), but no difference in decrease of muscle pH (from 7.0-7.3 to 5.9-6.0 at measurement 36 h after death). Higher rigor index at second measurement 2 h after death in uncrowded than crowded JUVENILES (ca 70% versus 50% relative difference to 0% at death), but no difference in time and magnitude of peak of rigor index (at measurement 12 h after death, ca 110%) and decrease of rigor index until 48 h after death. Tendency of higher number of JUVENILES with rigor score 4 (very strong rigor) at measurement 6 h after death in crowded than uncrowded JUVENILES (70% versus 58%) and rigor score 5 (rod-like rigor) at measurement 12 h after death (70% versus 43%) 41.
• LAB: JUVENILES either placed in ice water (2-4 °C) or CO2 supersaturated seawater. No opercular movement and no reaction to manipulation after 16 min in CO2 narcosis, 34 min in ice asphyxia, and 128 min in control group of air asphyxia. No difference in onset of rigor mortis (at second measurement 2 h after death), but resolution of rigor mortis later under CO2 narcosis (after sixth measurement 72 h after death) and ice asphyxia (after fourth measurement 24 h after death) than in air asphyxia (after 2 h after death). No decrease in muscle pH under ice asphyxia; no difference in onset of decrease under CO2 narcosis and air asphyxiation (at third measurement 9 h after death), but further decrease under CO2 narcosis until end of observation and increase under air asphyxia. No difference in onset of degradation in sensorial quality (at second measurement 2 h after death), but higher quality under ice asphyxia and CO2 narcosis compared to air asphyxia immediately after death (87.9-92.9% versus 61.3% of 100% fresh quality). Lower cortisol (ca 375 ng/mL versus 540 ng/mL) and glucose levels (ca 90-11 mg/dL versus ca 340 mg/dL) under ice asphyxia and CO2 narcosis than air asphyxia 42.
• LAB: JUVENILES in 215.5 L tanks. After five weeks, subjected to either anaesthesia with clove oil (2 min), anaesthesia with 2-phenoxyethanol (2 min), percussive stunning, immersion in ice-water slurry (1:2) for 10 min, chilling on ice for 20 min, combination of clove oil and immersion in ice-water-slurry. Lower muscle pH under two anaesthesia methods and percussive stunning compared to ice-water slurry, ice, and combination of clove oil and ice-water slurry (7.04-7.13 versus 7.29-7.39). Combination of clove oil and ice-water slurry was less stressful than other methods while maintaining flesh quality, but clove oil has not been approved for use on food FISHES 55.

collapse