A cost of reproduction in male Atlantic cod (Gadus morhua)

2010 ◽  
Vol 88 (6) ◽  
pp. 595-600 ◽  
Author(s):  
Jon E. Skjæraasen ◽  
Justin J. Meager ◽  
Jeffrey A. Hutchings
Keyword(s):  
Mass Loss ◽  
Gadus Morhua ◽  
Atlantic Cod ◽  
Reproductive Behaviour ◽  
Cost Of Reproduction ◽  
Male Reproductive Success ◽  
Honest Signal ◽  
Broadcast Spawning ◽  
The Cost ◽  
Considerable Body

In many species, females are thought to base their choice of mate on quality, which males signal through displays and body ornamentation. One important question is whether these signals represent an honest reflection of quality so that they carry an intrinsic cost to the male. A considerable body of evidence has revealed complex mating behaviours in gadoid fish, such as Atlantic cod ( Gadus morhua L., 1758), for which male reproductive success may be related to some form of female choice. However, if present, the cost of male signalling is not clear. To test the hypothesis that male behavioural displays are energetically costly, we quantified the number of displays initiated by males during spawning, and their corresponding mass loss, in two separate experiments. The number of displays was positively associated with mass loss in both experiments, suggesting that reproductive displays are costly to males; they also may be regarded as an honest signal of quality upon which females could base their choice of mate. To our knowledge, this is the first study to demonstrate a cost of male reproductive behaviour in a broadcast-spawning fish.

Spawning behaviour of Atlantic cod, Gadus morhua: evidence of mate competition and mate choice in a broadcast spawner

1999 ◽  
Vol 56 (1) ◽  
pp. 97-104 ◽  
Author(s):  
Jeffrey A Hutchings ◽  
Todd D Bishop ◽  
Carolyn R McGregor-Shaw
Keyword(s):  
Mate Choice ◽  
Gadus Morhua ◽  
Dna Analysis ◽  
Atlantic Cod ◽  
Multiple Paternity ◽  
Reproductive Behaviour ◽  
Male Dominance ◽  
Male Body ◽  
Experimental Conditions ◽  
Spawning Period

We quantified individual differences in Atlantic cod, Gadus morhua, reproductive behaviour at a field-reported spawning density under experimental conditions. Marked individuals (nine females, seven males) were observed twice daily and videotaped continuously for 9 weeks at ambient photoperiod and temperature in a large tank (60 m3). Agonistic interactions appeared to maintain a size-based dominance hierarchy among males. Multiple paternity per spawning bout, revealed by microsatellite DNA analysis, suggested a link between dominance and fertilization success. Interactions between sexes were dominated by the circling of females by males. Predicated by vertical separation from males, and after descending to the bottom, a motionless female would be circled up to 17 times, often by one male per circling bout but by several males throughout the spawning period. Although circling frequency increased with male dominance and male body size, initiation and termination of this behaviour appeared to be under female control. Circling provides opportunities for males to gain individual access to reproductive females and for females to assess the quality of potential mates. Our evidence for nonrandom mate choice and for male-male competition and display has implications for Atlantic cod mating systems and effects of fishing on their reproductive success.

scholarly journals Metabolic cost of feeding in Atlantic Cod (Gadus morhua) larvae using microcalorimetry

2006 ◽  
Vol 63 (2) ◽  
pp. 335-339 ◽  
Author(s):  
Artie McCollum ◽  
Jessica Geubtner ◽  
Ione Hunt von Herbing
Keyword(s):  
Gadus Morhua ◽  
Atlantic Cod ◽  
Metabolic Cost ◽  
Specific Dynamic Action ◽  
Total Heat ◽  
Heat Output ◽  
Larval Life ◽  
First Feeding ◽  
The Cost ◽  
Aerobic And Anaerobic

Abstract A microcalorimeter that measures total heat output (μW) was used to determine total metabolic rate (aerobic and anaerobic) and the cost of feeding (specific dynamic action, SDA) in larval Atlantic cod (Gadus morhua) from hatching to 4 weeks post-hatch at 10°C. Total heat output increased throughout development from 2.14 μW at first-feeding to 23.72 μW at 4 weeks post-hatch. SDA was determined by comparing the total heat output among unfed larvae and fed larvae simultaneously. Total heat output increased in the first 2 h after feeding with rotifers (Brachionus sp.) and Artemia, remained high for up to 10 h, was significantly higher in fed larvae than in unfed larvae, and ranged from 16.56 μW at first-feeding to 47.84 μW at 4 weeks post-hatch. The differences in total heat output between unfed and fed larvae were 14.42 μW and 24.12 μW, representing an increase in metabolic cost of feeding by a factor of 1.67 over the first 4 weeks of larval life. That the metabolic cost of feeding increased with development and remained elevated suggests that cod larvae allocate a large part of their energy budget to growth in order to meet the demands of their fast growth rates.

scholarly journals Reproductive investment in Atlantic cod populations off Newfoundland: Contrasting trends between males and females

FACETS ◽  
2017 ◽  
Vol 2 (2) ◽  
pp. 660-681 ◽  
Author(s):  
Loïc Baulier ◽  
M. Joanne Morgan ◽  
George R. Lilly ◽  
Ulf Dieckmann ◽  
Mikko Heino
Keyword(s):  
Life History Theory ◽  
Gadus Morhua ◽  
Atlantic Cod ◽  
Temporal Trends ◽  
Reproductive Investment ◽  
Male Reproductive Success ◽  
Density Dependent ◽  
Theoretical Predictions ◽  
Two Populations

Life history theory predicts selection for higher reproductive investment in response to increased mortality among mature individuals. We tested this prediction over the period from 1978 to 2013 for three populations of Atlantic cod ( Gadus morhua) off Newfoundland. These populations were heavily fished for a long period. We considered changes in standardized gonad weight as a proxy for changes in gonadal investment. We accounted for the allometry between gonad and body weight, individual body condition, water temperature, and potential spatial and density-dependent effects. Males display significant temporal trends in gonadal investment in all populations; in agreement with theoretical predictions, these trends show increased gonadal investments during the earlier part of the time series when mortality was high, with the trends leveling off or reversing after the later imposition of fishing moratoria. In contrast, females display patterns that are less consistent and expected; significant trends are detected only when accounting for density-dependent effects, with females in two populations unexpectedly showing a long-term decline in gonadal investment. Our results support the hypothesis that fisheries-induced evolution has occurred in gonadal investment in males, but not in females, and suggest that gonadal investment is more important for male reproductive success than expected in this lekking species.

Male reproductive success and body size in Atlantic cod Gadus morhua L.

2001 ◽  
Vol 138 (6) ◽  
pp. 1077-1085 ◽  
Author(s):  
Not Available Not Available ◽  
Not Available Not Available ◽  
Not Available Not Available
Keyword(s):  
Body Size ◽  
Reproductive Success ◽  
Gadus Morhua ◽  
Atlantic Cod ◽  
Male Reproductive Success

Sexual dimorphism in pelvic fin length of Atlantic cod

2006 ◽  
Vol 84 (6) ◽  
pp. 865-870 ◽  
Author(s):  
Jon Egil Skjæraasen ◽  
Sherrylynn Rowe ◽  
Jeffrey A. Hutchings
Keyword(s):  
Sexual Dimorphism ◽  
Morphological Traits ◽  
Gadus Morhua ◽  
Atlantic Cod ◽  
Broadcast Spawning ◽  
Fitness Consequences ◽  
Sexual Bias ◽  
Future Work ◽  
Sexual Characteristic ◽  
Pelvic Fin

Behavioural differences between females and males may result in sexual dimorphism among morphological traits associated with these behaviours. In the broadcast-spawning Atlantic cod ( Gadus morhua L., 1758), release of gametes occurs during a “ventral mount” in which the male positions himself directly beneath the female while grasping her with his pelvic fins. Males also display the pelvic fins during agonistic encounters with other males. Based on data obtained from four Atlantic cod populations off Canada and Norway, we find clear evidence of sexual dimorphism in pelvic fin size, the fins being significantly larger in males than in females. Pelvic fin size was, however, not more variable than other morphological traits and was not correlated with body condition or drumming muscles mass (hypothesized to be a secondary sexual characteristic in this species). To our knowledge, this is the first study to demonstrate sexual dimorphism in any external morphological trait in a gadoid fish. Although the observed differences in pelvic fin size may be a product of sexual selection, we identify future work to test this hypothesis and to explore more fully the causes and fitness consequences of this sexual bias in Atlantic cod.

A strategy to detect fish discarding by combining onboard and onshore sampling

1997 ◽  
Vol 54 (12) ◽  
pp. 2955-2963 ◽  
Author(s):  
Jacques Allard ◽  
Ghislain A Chouinard
Keyword(s):  
Gadus Morhua ◽  
Atlantic Cod ◽  
Nonparametric Test ◽  
Reference Points ◽  
Sampling Distribution ◽  
Small Fish ◽  
Conservation Problem ◽  
Cost Efficient ◽  
Using Data ◽  
The Cost

Discarding of small fish is considered to be an important conservation problem and has become illegal in some fisheries. We present a cost-efficient strategy to help enforce regulations against discarding. A discarding indicator is defined using the change in slope between two reference points on the empirical length-frequency density of the catch. This discarding indicator is then used according to the external distribution concept: the sampling distribution of the discarding indicator, when no discarding occurred, is obtained directly from samples taken by onboard observers; the value of the discarding indicator observed by onshore observers from a boat not covered by onboard observers is then compared with this sampling distribution. This procedure offers a nonparametric test for discarding. Application of the strategy is illustrated using data from the 1991 Atlantic cod (Gadus morhua) fishery in the southern Gulf of St. Lawrence. We describe several enforcement frameworks within which the method can be applied. The cost efficiency of the strategy comes from shifting resources from high-cost onboard observation to lower cost onshore observation.

scholarly journals Vertical dynamics and reproductive behaviour of farmed and wild Atlantic cod Gadus morhua

2009 ◽  
Vol 389 ◽  
pp. 233-243 ◽  
Author(s):  
JJ Meager ◽  
JE Skjæraasen ◽  
A Fernö ◽  
Ø Karlsen ◽  
S Løkkeborg ◽  
...  
Keyword(s):  
Gadus Morhua ◽  
Atlantic Cod ◽  
Reproductive Behaviour

scholarly journals Depensation, probability of fertilization, and the mating system of Atlantic cod (Gadus morhua L.)

2004 ◽  
Vol 61 (7) ◽  
pp. 1144-1150 ◽  
Author(s):  
Sherrylynn Rowe ◽  
Jeffrey A. Hutchings ◽  
Dorte Bekkevold ◽  
Ana Rakitin
Keyword(s):  
Population Size ◽  
Gadus Morhua ◽  
Atlantic Cod ◽  
Fertilization Rate ◽  
Effective Population ◽  
Broadcast Spawning ◽  
The North ◽  
Research Programmes ◽  
The North Sea ◽  
Census Population Size

Abstract Atlantic cod (Gadus morhua L.) have been severely overexploited and are currently at historic population lows, having declined 90% in the North Sea and 99% off northeast Newfoundland in recent decades. Slow rates of recovery and continuing declines may be attributable to depensation, defined as a reduction in per capita growth rate concomitant with reduced population size. Several potential causes of depensation relate to low mating success and consequent reduced production of offspring. We explore the empirical basis of one of these in Atlantic cod using egg fertilization and male abundance data obtained from 21 experimental populations generated by three independent research programmes. We find support for the hypotheses that (a) fertilization rate declines with abundance and (b) variance in fertilization rate increases as population size declines. The former identifies one potential mechanism underlying depensation in Atlantic cod. The latter has negative genetic consequences for effective population size (Ne), resulting in a decline in the ratio of Ne to census population size (Ne/Nc) with declining abundance. Our results may have general implications for the conservation biology of broadcast-spawning marine fish, particularly those with mating systems similar to that of Atlantic cod.

scholarly journals Extreme spawning-site fidelity in Atlantic cod

2011 ◽  
Vol 68 (7) ◽  
pp. 1472-1477 ◽  
Author(s):  
Jon Egil Skjæraasen ◽  
Justin J. Meager ◽  
Ørjan Karlsen ◽  
Jeffrey A. Hutchings ◽  
Anders Fernö
Keyword(s):  
Population Dynamics ◽  
Marine Fish ◽  
Site Fidelity ◽  
Gadus Morhua ◽  
Atlantic Cod ◽  
Spatial Scales ◽  
Local Population ◽  
Coastal Regions ◽  
Broadcast Spawning ◽  
Spawning Site

Abstract Skjæraasen, J. E., Meager, J. J., Karlsen, Ø., Hutchings, J. A., and Fernö, A. 2011. Extreme spawning-site fidelity in Atlantic cod. – ICES Journal of Marine Science, 68: 1472–1477. Based on a 3-year mark-recapture study, evidence is provided of spawning-site fidelity in Atlantic cod (Gadus morhua) at a scale (<1 km) smaller than documented previously. Coastal regions where barriers to dispersal exist may allow for local population dynamics and adaptation to develop in broadcast-spawning marine fish at extremely fine spatial scales.

Conservation of Piping Plover (Charadrius melodus) in North America: science, successes, and challenges1This review is part of the virtual symposium “Flagship Species – Flagship Problems” that deals with ecology, biodiversity and management issues, and climate impacts on species at risk and of Canadian importance, including the polar bear (Ursus maritimus), Atlantic cod (Gadus morhua), Piping Plover (Charadrius melodus), and caribou (Rangifer tarandus).

2011 ◽  
Vol 89 (5) ◽  
pp. 401-418 ◽  
Author(s):  
C.L. Gratto-Trevor ◽  
S. Abbott
Keyword(s):  
Gadus Morhua ◽  
Rangifer Tarandus ◽  
Atlantic Cod ◽  
Public Support ◽  
Climate Impacts ◽  
Piping Plover ◽  
Charadrius Melodus ◽  
Predator Management ◽  
Piping Plovers ◽  
The Cost

There are only about 8000 Piping Plovers ( Charadrius melodus Ord, 1834) in existence. Because they depend on environments that are under intense human pressures and controls in both their breeding and wintering grounds, these birds and their habitats are highly managed in many areas across their range. Efforts to recover this endangered and threatened species have engaged thousands of people from Newfoundland to the Caribbean, and have provoked a ground-swell of public support and, at times, fury, as well as a considerable body of research. Although populations have increased substantially in the U.S. Atlantic and U.S. Great Lakes, this is not true of all regions. Significant issues still exist with respect to the efficacy of predator management; need for more accurate model input information; effects of climate, pollutants, and water management; habitat loss and degradation from recreation and development; and whether the cost and effort of management for this species can be maintained or increased where needed.

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