scholarly journals Rebuilding Atlantic Cod: Lessons from a Spawning Ground in Coastal Newfoundland

2008 ◽  
Author(s):  
G.A. Rose ◽  
I.R. Bradbury ◽  
B deYoung ◽  
S.B. Fudge ◽  
G.I. Lawson ◽  
...  
Keyword(s):  
Atlantic Cod ◽  
Spawning Ground

Reproductive interactions between fugitive farmed and wild Atlantic cod (Gadus morhua) in the field

2010 ◽  
Vol 67 (8) ◽  
pp. 1221-1231 ◽  
Author(s):  
Justin J. Meager ◽  
Jon Egil Skjæraasen ◽  
Anders Fernö ◽  
Svein Løkkeborg
Keyword(s):  
Mating System ◽  
Gadus Morhua ◽  
Atlantic Cod ◽  
Spatial Dynamics ◽  
Wild Fish ◽  
Spawning Ground ◽  
Males And Females ◽  
Farmed Escapees ◽  
Ultrasonic Transmitters

Atlantic cod ( Gadus morhua ) are being increasingly farmed in net pens adjacent to coastal populations that are currently at historic lows. One concern is that farmed escapees enter local spawning shoals and mate with wild cod. We tested for the potential of escaped farmed cod to interact and hybridize with wild fish by examining the spatial dynamics of, and associations between, fish tagged with ultrasonic transmitters. Based on these data, we also investigated the basic mating system of cod in the field. The spawning ground was best described as a lekking arena. Wild males aggregated near the seafloor and associations between individuals were frequent. Wild females had a pelagic and dispersed distribution and rarely associated with each other. Associations between individual wild males and females were also infrequent. Farmed males rarely associated with wild fish and had core usage areas above the wild males, suggesting that they were not admitted into the spawning arena. Farmed females were over the spawning arena more frequently than wild females and often associated with wild males at the depth of the spawning arena, indicating potential mating with wild males and the possibility of courtship interference. Hence, hybridization between escaped farmed and wild cod is likely.

scholarly journals Home range and elevated egg densities within an inshore spawning ground of coastal cod

2007 ◽  
Vol 64 (5) ◽  
pp. 920-928 ◽  
Author(s):  
Sigurd Heiberg Espeland ◽  
Ailin Fernløf Gundersen ◽  
Esben Moland Olsen ◽  
Halvor Knutsen ◽  
Jakob Gjøsæter ◽  
...  
Keyword(s):  
Home Range ◽  
Site Fidelity ◽  
Gadus Morhua ◽  
Atlantic Cod ◽  
Generalized Additive Models ◽  
Spatial Dynamics ◽  
Additive Models ◽  
Spawning Season ◽  
Spawning Ground ◽  
Spawning Site

Abstract Espeland, S. H., Gundersen, A. F., Olsen, E. M., Knutsen, H., Gjøsæter, J., and Stenseth, N. C. 2007. Home range and elevated egg densities within an inshore spawning ground of coastal cod. – ICES Journal of Marine Science, 64: 920–928. Atlantic cod (Gadus morhua) along the Norwegian Skagerrak coast are structured into genetically distinct local populations. Mechanisms contributing to this genetic structure may include spawning site fidelity of adult cod as well as retention of pelagic early life stages close to the spawning grounds. Spawning in sheltered inshore localities is likely to favour retention of eggs and larvae, the opposite situation to offshore spawning. A combined study was made of area utilization by adult cod and the distribution of cod eggs within an inshore locality of the Norwegian Skagerrak coast. The behaviour of adult cod was studied using acoustic telemetry and kernel modelling, and eggs were sampled throughout the spawning season. Generalized additive models were applied to test hypotheses about the spatial dynamics of the eggs, and the best model described a central spawning area that retained its integrity through time. Adult cod were confined to small parts of the study area and remained there throughout the spawning season. The average home range of the adult cod was 27 ha. Overall, the study demonstrated two mechanisms by which coastal (i.e. inshore) cod maintain their population structure: spawning site fidelity and the spatial dynamics of their eggs.

scholarly journals Fine-scale diel and gender-based patterns in behaviour of Atlantic cod (Gadus morhua) on a spawning ground in the Western Gulf of Maine

2014 ◽  
Vol 71 (6) ◽  
pp. 1474-1489 ◽  
Author(s):  
Micah J. Dean ◽  
William S. Hoffman ◽  
Douglas R. Zemeckis ◽  
Michael P. Armstrong
Keyword(s):  
Gulf Of Maine ◽  
Atlantic Cod ◽  
Adjacent Area ◽  
Fine Scale ◽  
Spawning Ground ◽  
Laboratory Studies ◽  
Aggregation Site ◽  
Aggregation Behaviour ◽  
Spawning Behaviour ◽  
Gender Based

Abstract Understanding the influence of spawning behaviour on the fine-scale distribution of Atlantic cod is essential to the design of effective conservation measures. Laboratory studies suggest that spawning activity occurs primarily at night, yet no field studies have evaluated the influence of diel period on the behaviour of individual wild spawning cod. Using an acoustic telemetry positioning system, the fine-scale movements of spawning cod were observed in situ as they returned to the same spawning location over consecutive seasons. The resulting data identify clear gender-based diel patterns in space use and aggregation behaviour among cod on a spawning ground. During the day, females remained aggregated in one small location that varied little within and between years. Males also aggregated during the day, but occupied a much larger adjacent area. At night, individual males sought out separate small territories while females generally remained near their daytime aggregation site, making periodic excursions into the surrounding area. These patterns were surprisingly stable over the 2 years of observation, indicating little interannual variability in spawning behaviour. This study provides an unprecedented examination of the natural spawning behaviour of Atlantic cod, and makes connections between earlier laboratory studies and field observations.

Multiyear homing of Atlantic cod to a spawning ground

2001 ◽  
Vol 58 (12) ◽  
pp. 2325-2329 ◽  
Author(s):  
D Robichaud ◽  
G A Rose
Keyword(s):  
North Atlantic ◽  
Gadus Morhua ◽  
Atlantic Cod ◽  
Spawning Season ◽  
Spawning Ground ◽  
Long Distance ◽  
Tag Loss ◽  
Sea Bed ◽  
Placentia Bay

Long-term sonar transmitting tags were implanted in 27 female and 21 male cod (Gadus morhua) at the Bar Haven spawning ground in Placentia Bay, Newfoundland, in April 1998. Two thirds of tagged fish were relocated. All relocations during the 1999 and 2000 spawning seasons were within 10 km of the tagging site, the majority being within a few hundred metres. No tagged fish were relocated at other spawning grounds or elsewhere in the bay during the spawning season. Outside the spawning season, several tagged fish were relocated in other parts of the bay at ranges of a few kilometres to 110 km from the tagging site, as were 13 of 15 fishery returns (2 returns from several hundred kilometres outside the bay). Homing rates in 1999 and 2000 were 39% and 53%, respectively, after adjustments for tag loss, mortality, misreporting, and relocation efficiency based on returns from a sea-bed beacon tag left at the Bar Haven grounds. Multiyear homing was observed in 26% of cod. This study provides the first direct evidence that cod undertaking long-distance feeding migrations may home to a specific spawning ground in consecutive years, and a hypothesis for the slow recolonisation rates observed in North Atlantic cod stocks.

Effects of temperature on life history set the sensitivity to fishing in Atlantic cod Gadus morhua

2014 ◽  
Vol 514 ◽  
pp. 217-229 ◽  
Author(s):  
HY Wang ◽  
LW Botsford ◽  
JW White ◽  
MJ Fogarty ◽  
F Juanes ◽  
...  
Keyword(s):  
Life History ◽  
Gadus Morhua ◽  
Atlantic Cod ◽  
Effects Of Temperature

Responses of Atlantic cod Gadus morhua head kidney leukocytes to phytase produced by gastrointestinal-derived bacteria

2009 ◽  
Vol 36 (4) ◽  
pp. 883-891 ◽  
Author(s):  
Carlo C. Lazado ◽  
Christopher Marlowe A. Caipang ◽  
Sanchala Gallage ◽  
Monica F. Brinchmann ◽  
Viswanath Kiron
Keyword(s):  
Gadus Morhua ◽  
Atlantic Cod ◽  
Head Kidney

scholarly journals Optimization of the flow conditions in the spawning ground of the Chinese sturgeon (Acipenser sinensis) through Gezhouba Dam generating units

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Anyang Huang ◽  
Jinzhong Yao ◽  
Jiazhi Zhu ◽  
Xingchen Gao ◽  
Wei Jiang
Keyword(s):  
Spawning Ground ◽  
Chinese Sturgeon ◽  
Flow Conditions ◽  
Velocity Measurements ◽  
Acipenser Sinensis ◽  
Critically Endangered Species ◽  
Gezhouba Dam ◽  
Opening Mode ◽  
Suitable Area ◽  
Good Agreement

AbstractChinese sturgeon (Acipenser sinensis) is a critically endangered species, and waters downstream from Gezhouba Dam are the only known spawning ground. To optimize the velocity conditions in the spawning ground by controlling the opening mode of Gezhouba Dam generator units, a mathematical model of Chinese sturgeon spawning ground was established in FLOW-3D. The model was evaluated with velocity measurements, and the results were determined to be in good agreement. By inverting the 2016–2019 field monitoring results, the model shows that the preferred velocity range for Chinese sturgeon spawning is 0.6–1.5 m/s. Velocity fields of different opening modes of the generator units were simulated with identical discharge. The suitable-velocity area was maximal when all units of Dajiang Plant of Gezhouba Dam were open. For discharges below 12,000 m3/s, most of the area was suitable; for discharges above 12,000 m3/s, the suitable area rapidly decreased with increasing discharge. A comparison of suitable areas under high-flow showed that at discharges of 12,000–15,000 m3/s, opening 11–13 units on the left side was optimal. For discharges above 15,000 m3/s, all units should be open. We used these results to recommend a new operation scheme to support the conservation of Chinese sturgeon.

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