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.

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.

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

2004 ◽  
Vol 82 (9) ◽  
pp. 1391-1398 ◽  
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.

scholarly journals The expression of secondary sexual characteristics in recruit- and repeat-spawning farmed and wild Atlantic cod (Gadus morhua)

2008 ◽  
Vol 65 (9) ◽  
pp. 1710-1716 ◽  
Author(s):  
Jon Egil Skjæraasen ◽  
Justin J. Meager ◽  
Ørjan Karlsen
Keyword(s):  
Gadus Morhua ◽  
Atlantic Cod ◽  
Mating Behaviour ◽  
Secondary Sexual Characteristics ◽  
Sexual Characteristics ◽  
In The Wild ◽  
Defensive Behaviours ◽  
Farmed Escapees ◽  
Pelvic Fin ◽  
Secondary Sexual

Abstract Skjæraasen, J. E., Meager, J. J., and Karlsen, Ø. 2008. The expression of secondary sexual characteristics in recruit- and repeat-spawning farmed and wild Atlantic cod (Gadus morhua). – ICES Journal of Marine Science, 65: 1710–1716. We examined the expression of the two known secondary sexual characteristics of Atlantic cod, the pelvic fin and the drumming muscle, in farmed and wild cod stemming from the same population. Farmed and wild males had longer pelvic fins and larger drumming muscles than females, but wild cod had longer fins than farmed cod. The size of the drumming muscle of males was similar among wild and farmed cod, but farmed females had smaller muscles than their wild counterparts. Repeat-spawning wild males tended to invest less in drumming-muscle mass and more in pelvic-fin growth than recruit-spawning fish, whereas the reverse was true for farmed males. Males use pelvic fins to embrace females during ventral mounts, a key mating behaviour, and display them to other males during agonistic interactions. The drumming muscle is used by males to produce sound during courtship and aggressive displays, whereas females only use sound outside the spawning season, for agonistic and defensive behaviours that are unlikely to be as important in the farming environment. The results are discussed in the context of the reproductive success of farmed escapees in the wild.

scholarly journals Genetic variation in life-history reaction norms in a marine fish

2007 ◽  
Vol 274 (1619) ◽  
pp. 1693-1699 ◽  
Author(s):  
Jeffrey A Hutchings ◽  
Douglas P Swain ◽  
Sherrylynn Rowe ◽  
James D Eddington ◽  
Velmurugu Puvanendran ◽  
...  
Keyword(s):  
Environmental Change ◽  
Gadus Morhua ◽  
Cold Water ◽  
Atlantic Cod ◽  
Spatial Scales ◽  
Larval Growth ◽  
Common Garden ◽  
Marine Fishes ◽  
Reaction Norms ◽  
Broadcast Spawning

Neither the scale of adaptive variation nor the genetic basis for differential population responses to the environment is known for broadcast-spawning marine fishes. Using a common-garden experimental protocol, we document how larval growth, survival and their norms of reaction differ genetically among four populations of Atlantic cod ( Gadus morhua ). These traits, and their plastic responses to food and temperature, differed across spatial scales at which microsatellite DNA failed to detect population structure. Divergent survival reaction norms indicate that warm-water populations are more sensitive to changes in food, whereas cold-water populations are more sensitive to changes in temperature. Our results suggest that neither the direction nor the magnitude of demographic responses to environmental change need be the same among populations. Adaptive phenotypic plasticity, previously undocumented in marine fishes, can significantly influence the probability of recovery and persistence of collapsed populations by affecting their ability to respond to natural and anthropogenic environmental change.

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.

Temporal variability in offspring quality and individual reproductive output in a broadcast-spawning marine fish

2017 ◽  
Vol 75 (4) ◽  
pp. 1353-1361 ◽  
Author(s):  
Nancy E Roney ◽  
Rebekah A Oomen ◽  
Halvor Knutsen ◽  
Esben M Olsen ◽  
Jeffrey A Hutchings
Keyword(s):  
Body Size ◽  
Temporal Variability ◽  
Gadus Morhua ◽  
Reproductive Output ◽  
Atlantic Cod ◽  
Offspring Quality ◽  
Spawning Period ◽  
Broadcast Spawning ◽  
Batch Number ◽  
Individual Fitness

Abstract The protracted spawning period of broadcast-spawning marine fishes has potential to generate considerable variability in metrics of individual reproductive output. We undertook a temporally detailed genetic study of larvae produced by Atlantic cod (Gadus morhua) from two spatially proximate populations spawning under controlled semi-natural conditions over 94 days. Based on daily samples of larvae (n = 4489 in total), we document fine-scaled temporal changes in, and correlates of, offspring phenotype and reproductive output (egg batches produced or fertilized). Larval length and standardized yolk-sac volume declined 11 and 49% over the spawning period, respectively. The adaptive significance of these trends is unclear. Longer, heavier females produced longer, better-provisioned larvae. Body size affected the number of egg batches to which an individual contributed genetically but not spawning duration. Males contributed gametes to a greater number of egg batches (19.5 vs. 9.2), and spawned over a longer period of time (48.9 vs. 30.8 days), than females. After accounting for body size and condition, egg batch number and spawning duration differed between adjacent populations separated by &lt; 10 km. Our work highlights the need to understand the environmental and adaptive causes of temporal variability in offspring quality and its consequences to individual fitness and per capita population growth in batch-spawning fishes.

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

Some recent data on sperm morphology and motility kinetics in Atlantic cod (Gadus morhua L.)

2021 ◽  
Author(s):  
Sayyed Mohammad Hadi Alavi ◽  
Azadeh Hatef ◽  
Ian A.E. Butts ◽  
Olga Bondarenko ◽  
Jacky Cosson ◽  
...  
Keyword(s):  
Gadus Morhua ◽  
Sperm Morphology ◽  
Atlantic Cod
Sign in / Sign up

Export Citation Format

Share Document