Family differences on triploid induction, sexual maturation and its contribution to sea cage performance of Atlantic cod, Gadus morhua

Abstract In marine fisheries, considerable development has occurred in capture technology. Yet, some of the current fishing methods impact the environment by large greenhouse gas emission, harmful effects to benthic communities, and/or high bycatch of juvenile and unwanted species. It is proposed that for some fish species these deficiencies could be mitigated by classical conditioning using sound and food reward to concentrate wild fish before capture with environmentally friendly fishing gear. Atlantic cod (Gadus morhua), which globally is among the fish species with the highest landed value, can be acoustically trained. In a sea cage, it takes about a week to train a group of naïve cod to associate low frequency (250 Hz) sound with food, whereas the training of a group of naïve cod accompanied with one trained cod takes less than a day. In inshore areas, it takes a few weeks to attract thousands of cod to stations where food is regularly delivered. These conditioned cod wait at the stations for their meals and do not mingle much with the unconditioned cod which hunt for wild prey. It is suggested that by calling acoustically conditioned fish between stations, a much larger number of naïve fish can be gathered. This so-called fish aggregating sound technique (FAST) may thus facilitate the accumulation of wild fish and expedite their capture with a purse seine or a trap in a way that minimizes fuel consumption and mortality of juveniles and unwanted species. The operation of FAST requires exclusive rights of a designated fishing area. The exclusivity makes it possible to on-grow the fish in free-ranging schools and sea cages for several months to increase their size and food quality before capture.

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Photoperiod regulates the timing of sexual maturation, spawning, sex steroid and thyroid hormone profiles in the Atlantic cod (Gadus morhua)

Aquaculture ◽

10.1016/s0044-8486(03)00393-4 ◽

2004 ◽

Vol 229 (1-4) ◽

pp. 451-467 ◽

Cited By ~ 66

Author(s):

Birgitta Norberg ◽

Christopher L. Brown ◽

Olafur Halldorsson ◽

Kjetil Stensland ◽

Björn Thrandur Björnsson

Keyword(s):

Thyroid Hormone ◽

Sexual Maturation ◽

Gadus Morhua ◽

Atlantic Cod ◽

Sex Steroid

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Towards cod without spawning: artificial continuous light in submerged sea-cages maintains growth and delays sexual maturation for farmed Atlantic cod Gadus morhua

Aquaculture Environment Interactions ◽

10.3354/aei00067 ◽

2013 ◽

Vol 3 (3) ◽

pp. 245-255 ◽

Cited By ~ 4

Author(s):

ØJ Korsøen ◽

T Dempster ◽

JE Fosseidengen ◽

Ø Karlsen ◽

F Oppedal ◽

...

Keyword(s):

Sexual Maturation ◽

Gadus Morhua ◽

Atlantic Cod ◽

Continuous Light

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The role of seasonally altering photoperiod in regulating physiology in Atlantic cod (Gadus morhua). Part I. Sexual maturation

Canadian Journal of Fisheries and Aquatic Sciences ◽

10.1139/f06-169 ◽

2007 ◽

Vol 64 (1) ◽

pp. 84-97 ◽

Cited By ~ 49

Author(s):

Andrew Davie ◽

Mark JR Porter ◽

Niall R Bromage ◽

Herve Migaud

Keyword(s):

Sexual Maturation ◽

Gadus Morhua ◽

Atlantic Cod ◽

Reproductive Activity ◽

Continuous Illumination ◽

Natural Photoperiod ◽

Artificial Photoperiod ◽

Commercially Important ◽

Photoperiod Manipulation

While the Atlantic cod (Gadus morhua) displays clear seasonality in its reproductive cycle, the exact photic signal that entrains this rhythm is yet undefined. This present work developed a model to describe the photic regulation of reproduction in the species in comparison with other commercially important temperate teleosts. This was achieved through the strategic masking of the natural photoperiod cycle during the first 2 years of life with the application of continuous illumination. The results demonstrated that it is the falling autumnal photoperiod signal after the summer solstice, more specifically after October, that is responsible for recruiting individuals to enter the sexual maturation cycle. Furthermore, in all treatments where this signal was masked through the application of continuous illumination, there was no significant reproductive activity and growth was improved by up to 60% at 27 months posthatch. This information is of particular value to the developing cod aquaculture industry in which the management of reproduction using artificial photoperiod manipulation will be of vital economic importance.

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Sonic tracking of wild cod, Gadus morhua, in an inshore region of the Bay of Fundy: a contribution to understanding the impact of cod farming for wild cod and endangered salmon populations

ICES Journal of Marine Science ◽

10.1016/j.icesjms.2006.03.022 ◽

2006 ◽

Vol 63 (7) ◽

pp. 1364-1371 ◽

Cited By ~ 15

Author(s):

Paul Brooking ◽

Gino Doucette ◽

Steve Tinker ◽

Frederick G. Whoriskey

Keyword(s):

Gadus Morhua ◽

Atlantic Cod ◽

Late Summer ◽

Bay Of Fundy ◽

Release Point ◽

Passamaquoddy Bay ◽

The Mean ◽

Migration Corridor ◽

Sea Cage ◽

The Impact

Abstract Sea cage trials of Atlantic cod farming have begun in the Bay of Fundy region. We fitted inshore wild cod (n = 10) captured in the Quoddy region with sonic tags during the late summer of 2004 to provide data on their temporal and spatial residency and habitat usage, with a view to understanding the potential for impact between escaped farmed cod and wild cod and other fish species, particularly Atlantic salmon. Most of the tagged cod remained within a restricted corridor in the inshore zone, occupied deep water (75–130 m) within several kilometres of the release point, and undertook local movements. Three cod undertook more extensive movements; one fish emigrated offshore immediately, and two fish moved as far as 14 km from the release point before returning, 52–54 h later, to the area in which the other cod were located. The mean residence time in the inshore zone was 55 days. In the late autumn, there was a staggered pattern of departure from the coastal zone, although one fish over-wintered in Passamaquoddy Bay. Three of the nine cod that migrated offshore in autumn 2004 returned within a three-week period in May 2005, after a mean absence of 172 days, and reoccupied the inshore region inhabited the previous year. These cod left the region again after a mean residence of 120 days during the spring and summer. The presence of some of the tagged cod in the principal migration corridor for wild salmon smolts during the period of their migration suggests that escapes from cod farms could result in increased predation on salmon smolts from endangered populations.

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Neuroendocrine regulation of reproduction in Atlantic cod (Gadus morhua): Evidence of Eya3 as an integrator of photoperiodic cues and nutritional regulation to initiate sexual maturation

Comparative Biochemistry and Physiology Part A Molecular & Integrative Physiology ◽

10.1016/j.cbpa.2021.111000 ◽

2021 ◽

pp. 111000

Author(s):

A. Doyle ◽

M.E. Cowan ◽

H. Migaud ◽

P.J. Wright ◽

A. Davie

Keyword(s):

Sexual Maturation ◽

Gadus Morhua ◽

Atlantic Cod ◽

Neuroendocrine Regulation ◽

Nutritional Regulation ◽

Regulation Of Reproduction

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Continuous light delays sexual maturation and increases growth of Atlantic cod (Gadus morhua L.) in sea cages

ICES Journal of Marine Science ◽

10.1016/j.icesjms.2005.10.014 ◽

2006 ◽

Vol 63 (2) ◽

pp. 365-375 ◽

Cited By ~ 73

Author(s):

G.L. Taranger ◽

L. Aardal ◽

T. Hansen ◽

O.S. Kjesbu

Keyword(s):

Sexual Maturation ◽

Gadus Morhua ◽

Atlantic Cod ◽

Gonad Development ◽

Somatic Growth ◽

Continuous Light ◽

Reproductive Investment ◽

Spawning Season ◽

Commercial Fish ◽

Spawning Period

Abstract Prevention of early sexual maturation is essential in Atlantic cod (Gadus morhua) farming because maturity results in reduced growth, affects flesh quality, and may lead to increased mortality. In farmed cod, almost 100% of the fish mature at two years of age and often at a size of 1.5–2 kg. Two pilot experiments were conducted with cod in sea cages at a commercial fish farm in western Norway (60°N) to test the effect of additional continuous light (LL) on the timing of sexual maturation and somatic growth compared with controls under natural light (NL). In the NL groups, 100% maturation was indicated during the natural spawning period from February to April at the age of two years. By contrast, LL treatment from 27 June (15-month-old cod) or 2 September (18-month-old cod) onwards delayed gonad development by three to five months, reduced reproductive investment, and enhanced winter growth compared with the controls. Fish held at NL decreased in body weight during the spawning season (February–April), whereas LL-exposed fish appeared to continue to grow during their spawning season (May–August). LL-treated cod reached mean body weights of 2.90–3.13 kg within 28 months of hatching, whereas the controls reached 2.20–2.42 kg during the same period.

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