The Role of Circulating Catecholamines in the Ventilatory and                Hypertensive Responses to Hypoxia in the Atlantic Cod (Gadus                morhua)

More than 10 years after the collapse of Atlantic cod (Gadus morhua) fisheries in Canada, the role of increased seal populations in the decline and lack of recovery of the stocks continues to be discussed. Using removals and abundance indices from synthetic populations, we found that sequential population analysis can uncover trends in natural mortality. We used this approach to examine variation in natural mortality (M) of southern Gulf of St. Lawrence cod. M increased from the late 1970s to the mid-1990s but declined slightly recently. Results were consistent with previous work indicating that M increased in the 1980s. Changes in estimated M for this cod stock matched fluctuations in grey seal (Halichoerus grypus) abundance. The increase in grey seal abundance from the late 1970s to the mid-1990s corresponded with the increase in estimated M of cod over this time period. The correspondence between seal abundance and M of cod supports the hypothesis that seal predation may be a cause of increased M. However, the diet information available suggests that seals consume mainly juvenile cod, whereas our evidence for an increase in M is for larger cod (ages 3 years and older).

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Impacts of regular and random noise on the behaviour, growth and development of larval Atlantic cod ( Gadus morhua )

Proceedings of The Royal Society B Biological Sciences ◽

10.1098/rspb.2015.1943 ◽

2015 ◽

Vol 282 (1817) ◽

pp. 20151943 ◽

Cited By ~ 33

Author(s):

Sophie L. Nedelec ◽

Stephen D. Simpson ◽

Erica L. Morley ◽

Brendan Nedelec ◽

Andrew N. Radford

Keyword(s):

Growth And Development ◽

Gadus Morhua ◽

Atlantic Cod ◽

Acoustic Noise ◽

Random Noise ◽

Mitigation Measures ◽

Lower Body ◽

Body Width ◽

Sound Levels

Anthropogenic noise impacts behaviour and physiology in many species, but responses could change with repeat exposures. As repeat exposures can vary in regularity, identifying regimes with less impact is important for regulation. We use a 16-day split-brood experiment to compare effects of regular and random acoustic noise (playbacks of recordings of ships), relative to ambient-noise controls, on behaviour, growth and development of larval Atlantic cod ( Gadus morhua ). Short-term noise caused startle responses in newly hatched fish, irrespective of rearing noise. Two days of both regular and random noise regimes reduced growth, while regular noise led to faster yolk sac use. After 16 days, growth in all three sound treatments converged, although fish exposed to regular noise had lower body width–length ratios. Larvae with lower body width–length ratios were easier to catch in a predator-avoidance experiment. Our results demonstrate that the timing of acoustic disturbances can impact survival-related measures during development. Much current work focuses on sound levels, but future studies should consider the role of noise regularity and its importance for noise management and mitigation measures.

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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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The function of sound production by Atlantic cod as inferred from patterns of variation in drumming muscle mass

Canadian Journal of Zoology ◽

10.1139/z04-119 ◽

2004 ◽

Vol 82 (9) ◽

pp. 1391-1398 ◽

Cited By ~ 41

Author(s):

Sherrylynn Rowe ◽

Jeffrey A Hutchings

Keyword(s):

Sexual Selection ◽

Muscle Mass ◽

Morphological Traits ◽

Gadus Morhua ◽

Sound Production ◽

Atlantic Cod ◽

Size Condition ◽

Spawning Behaviour ◽

Fitness Benefits

We quantified variation in the mass of drumming muscles (the sound-producing musculature) among individual Atlantic cod (Gadus morhua L., 1758) for comparison with other evidence on the role of sexual selection in the evolution of sound production by this species. Based on 913 cod sampled from the Western Scotian Shelf in 2001–2002, we found that males had drumming muscles that were larger than those of females and that increased in mass prior to spawning and declined thereafter. Drumming muscle mass was highly variable, particularly among males, and generally more variable than other morphological traits (somatic mass and body length). This pattern of drumming muscle variation is consistent with the hypothesis that drumming muscles are influenced by sexual selection and suggests that sound production by males during the spawning season has fitness benefits, perhaps through a role in mate competition. Drumming muscle mass of spawning males was also positively associated with body size, condition, and fertilization potential, suggesting that sound production may be an indicator of the size of the signaler and may reveal information about individual quality. In conjunction with previous studies of sound production by Atlantic cod, our study underscores the potential importance of sound production to cod spawning behaviour.

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The role of seasonally altering photoperiod in regulating physiology in Atlantic cod (Gadus morhua). Part II. Somatic growth

Canadian Journal of Fisheries and Aquatic Sciences ◽

10.1139/f06-170 ◽

2007 ◽

Vol 64 (1) ◽

pp. 98-112 ◽

Cited By ~ 20

Author(s):

Andrew Davie ◽

Mark JR Porter ◽

Niall R Bromage ◽

Herve Migaud

Keyword(s):

Growth Factor ◽

Plasma Insulin ◽

Gadus Morhua ◽

Atlantic Cod ◽

Somatic Growth ◽

Growth Stimulation ◽

Continuous Illumination ◽

Insulin Like Growth Factor ◽

Factor I

Research to date has not clearly defined the role of photoperiod in regulating somatic growth in Atlantic cod (Gadus morhua). The present study followed individual growth performance, plasma insulin-like growth factor-I, and relative liver size in response to a range of experimental photoperiod treatments where populations were transferred from an ambient photoperiod regime to continuous illumination at strategic times during the first 2 years of life. While this work demonstrated that application of continuous illumination could directly stimulate somatic growth, this growth stimulation is transitory with no accumulative effect of prolonged exposure to continuous illumination. Importantly, it was apparent that the photic inhibition of maturation realized a far more significant growth stimulation, and in populations where this occurred, sexually dimorphic growth patterns became apparent. Plasma insulin-like growth factor-I displays a seasonal rhythm correlated with ambient temperature under natural photic conditions and in certain circumstances could be used as an accurate predictor of growth rate. Overall, this work further refines the guidelines on photoperiod management during commercial ongrowing of the species to help realize the maximum economic potential of cod aquaculture.

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Finny Merchandise: The Atlantic Cod (Gadus morhua) Trade in Gold Rush–Era San Francisco, California

10.31235/osf.io/9dmeb ◽

2021 ◽

Author(s):

Cyler Conrad ◽

Upuli DeSilva ◽

Brittany Bingham ◽

Brian Kemp ◽

Kenneth W. Gobalet ◽

...

Keyword(s):

San Francisco ◽

Ancient Dna ◽

Gadus Morhua ◽

East Coast ◽

Atlantic Cod ◽

The United States ◽

Gold Rush ◽

Pacific Cod ◽

Deep Waters

During California’s Gold Rush of 1849–1855, thousands of miners rushed to San Francisco, Sacramento, and elsewhere throughout northern California, creating a significant demand for food. Here we investigate the role of Atlantic cod (Gadus morhua) and Pacific cod (G. macrocephalus) during the Gold Rush era using historical records, ancient DNA, and vertebral morphology in the cod assemblage recovered from Thompson’s Cove (CA-SFR-186H), a Gold Rush–era site in San Francisco. From the 18 cod bones recovered from Thompson’s Cove, our analysis of five specimens for ancient DNA indicates that Atlantic cod were imported during the 1850s, likely as a (largely) deboned, dried and salted product from the East Coast of the United States. Curiously, while locally available in very deep waters off the California coast, Pacific cod were minimally fished during the 1850s and became abundantly available in the 1860s after an Alaska-based fishery developed.

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