Extreme male-skewed sex ratios on spawning grounds for Atlantic cod Gadus morhua with typical coastal cod signatures of the Pan I (pantophysin) locus

Fevolden, Svein-Erik; Westgaard, Jon‐Ivar; Pedersen, Torstein

doi:10.3354/sedao00013

Cited by 5 publications

(10 citation statements)

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“…This was also found in a study of the moderately sexually size dimorphic Alaskan sockeye salmon ( Oncorhynchus nerka ), where size‐selective harvesting resulted in female‐biased adult sex ratios (Kendall & Quinn, ). Sex‐selective harvesting can be intentional through sex‐specific harvest limits or quotas (Clark & Tait, ; Sato et al, ), or unintentional due to sex‐specific behaviors and timing or location of harvest (Fevolden et al, ; Robinson et al, ).…”

Section: Discussionmentioning

confidence: 99%

“…The fertility of individuals of the same sex and individuals of the opposite sex can be affected if the survival of one sex decreases due to selective harvesting, or other factors such as disease (Guerra‐Silveira & Abad‐Franch, ), predation (Boukal, Berec, & Krivan, ), or environmental factors (Bodkin, Burdin, & Ryazanov, ). Males and females in harvested populations can be targeted differently due to sex‐specific size or shape (Fairbairn et al, ; Kendall & Quinn, ), behavior (e.g., sex‐specific depth preferences and arrival time at spawning ground; Fevolden, Westgaard, & Pedersen, ), or human preference (e.g., trophy hunting; Ginsberg & Milner‐Gulland, ; Milner‐Gulland et al, ). When one sex is harvested disproportionately, it can have detrimental consequences for the population (Fenberg & Roy, ).…”

Section: Introductionmentioning

confidence: 99%

“…In many exploited populations, harvesting is size-selective (Fenberg & Roy, 2008;Zhou et al, 2010). Sexual size dimorphism is widespread in animals (Andersson, 1994;Fairbairn, Blanckenhorn, & Szekely, 2007), yet most of our knowledge on the effects of selective harvesting of sex-structured species is derived from one-sex or asexual demographic population models (but see Lindström, 1998).…”

Section: Introductionmentioning

confidence: 99%

“…Two-sex models may also provide more precise population projections as many species have sex-specific vital rates (Fairbairn et al, 2007;Trivers, 1972). When individuals of a certain size and/or sex are harvested, it can result in detrimental changes in the population growth rate, structure, and sex ratio (e.g., Fenberg & Roy, 2008;Ginsberg & Milner-Gulland, 1994;Greene, Umbanhowar, Mangel, & Caro, 1998;Hamilton et al, 2007;Kendall & Quinn, 2012;Milner, Nilsen, & Andreassen, 2007;Milner-Gulland et al, 2003;Mysterud et al, 2002;Sato, Ashidate, Wada, & Goshima, 2005), which are not detectable in one-sex or asexual models. Size-structured dynamics are increasingly studied using integral projection models (IPMs; Easterling, Ellner, & Dixon, 2000;Ellner, Childs, & Rees, 2016).…”

Section: Introductionmentioning

confidence: 99%

“…Males and females in harvested populations can be targeted differently due to sex-specific size or shape (Fairbairn et al, 2007;Kendall & Quinn, 2012), behavior (e.g., sex-specific depth preferences and arrival time at spawning ground; Fevolden, Westgaard, & Pedersen, 2015), or human preference (e.g., trophy hunting; Ginsberg & Milner-Gulland, 1994;Milner-Gulland et al, 2003). When one sex is harvested disproportionately, it can have detrimental consequences for the population (Fenberg & Roy, 2008).…”

Section: Introductionmentioning

confidence: 99%

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Effects of size‐ and sex‐selective harvesting: An integral projection model approach

Stubberud

Vindenes

Vøllestad

et al. 2019

Ecology and Evolution

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Harvesting is often size‐selective, and in species with sexual size dimorphism, it may also be sex‐selective. A powerful approach to investigate potential consequences of size‐ and/or sex‐selective harvesting is to simulate it in a demographic population model. We developed a population‐based integral projection model for a size‐ and sex‐structured species, the commonly exploited pike (Esox lucius). The model allows reproductive success to be proportional to body size and potentially limited by both sexes. We ran all harvest simulations with both lower size limits and slot limits, and to quantify the effects of selective harvesting, we calculated sex ratios and the long‐term population growth rate (λ). In addition, we quantified to what degree purely size‐selective harvesting was sex‐selective, and determined when λ shifted from being female to male limited under size‐ and sex‐selective harvesting. We found that purely size‐selective harvest can be sex‐selective, and that it depends on the harvest limits and the size distributions of the sexes. For the size‐ and sex‐selective harvest simulations, λ increased with harvest intensity up to a threshold as females limited reproduction. Beyond this threshold, males became the limiting sex, and λ decreased as more males were harvested. The peak in λ, and the corresponding sex ratio in harvest, varied with both the selectivity and the intensity of the harvest simulation. Our model represents a useful extension of size‐structured population models as it includes both sexes, relaxes the assumption of female dominance, and accounts for size‐dependent fecundity. The consequences of selective harvesting presented here are especially relevant for size‐ and sex‐structured exploited species, such as commercial fisheries. Thus, our model provides a useful contribution toward the development of more sustainable harvesting regimes.

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