Distribution, relative abundance, and reproductive output of spawning female blue crab (Callinectes sapidus) in offshore waters of the Gulf of Mexico

Kemberling, Adam A.; Darnell, M. Zachary

doi:10.7755/fb.118.4.4

Cited by 8 publications

(3 citation statements)

References 15 publications

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“…Brood production was allowed to continue throughout the year, with no seasonality (Adkins 1972). Initial brood size was set at 3 million eggs (Prager et al 1990; Darnell et al 2009; Graham et al 2012; Kemberling and Darnell 2020), and subsequent brood sizes were assumed to decrease at a consistent rate of 5% per brood (Darnell et al 2009). Maximum brood size (i.e., brood size assuming that sufficient sperm were available) was thus calculated as

Maximum brood size = Maximum size of previous brood \times 0.95 .

…”

Section: Methodsmentioning

confidence: 99%

Evidence for Sperm Limitation in the Louisiana Blue Crab Spawning Stock

Olmi‐Graham

Darnell

2022

Trans Am Fish Soc

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Male‐targeted fishing pressure has the potential to skew population sex ratios and to result in sperm limitation in females, where the quantity or quality of sperm received during mating is insufficient for the female to achieve her full lifetime reproductive potential. Blue crabs Callinectes sapidus are heavily targeted by commercial and recreational fisheries throughout much of their range, with fishing pressure biased toward males. Additionally, blue crabs are particularly susceptible to sperm limitation because mating occurs during a short window following the female’s terminal molt and stored sperm is used to fertilize all future broods. We investigated sperm quantities in recently molted and mated female blue crabs in southeastern Louisiana to assess the potential for sperm limitation in this area. Sperm quantities were an order of magnitude lower than those previously observed in other areas. Brood production modeling indicated that most of the female blue crabs in this region are heavily sperm limited and unable to achieve their lifetime spawning potential. On a population level, this sperm limitation may be partially responsible for recent declines in landings and estimates of abundance. Although insufficient data exist to assess the precise cause of this sperm limitation, these results should be incorporated into future stock assessments and management decisions for the Louisiana blue crab spawning stock.

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Maximum brood size = Maximum size of previous brood \times 0.95 .

…”

Section: Methodsmentioning

confidence: 99%

Evidence for Sperm Limitation in the Louisiana Blue Crab Spawning Stock

Olmi‐Graham

Darnell

2022

Trans Am Fish Soc

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“…Spawning and larval habitat may include both state and federal offshore waters. Large aggregations of spawning females occur around the barrier islands in state waters of the north-central GOM (Perry 1975;Anderson et al 2017) and in the Ship/Trinity/Tiger Shoal area in the territorial sea off Louisiana (Gelpi et al 2009;Kemberling and Darnell 2020).…”

Section: Life Historymentioning

confidence: 99%

Status and Management of the Blue Crab Fishery in the Gulf of Mexico

Perry

Anderson

Collins

2022

N American J Fish Manag

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Management of the blue crab Callinectes sapidus fishery in the Gulf of Mexico is the responsibility of the individual states under the purview of a regional management plan. States generally follow the "2-S" system of management, placing emphasis on size and sex. Despite management policies, harvest and juvenile abundances remain in decline. A significant trend toward decreasing harvest began in the early 2000s, with landings below average in 13 of the 20 years from 2000 to 2019. Since 2010, the fishery has maintained a lower but relatively stable harvest. There have been significant decreases in numbers of late-stage juveniles in fishery-independent trawl surveys, while numbers of megalopae and early juveniles have not exhibited declines. Postsettlement mortality is potentially driven by climate-related hydrological processes that structure the biotic community (predator guild) and nearshore habitats. Diversity of predators, few predation-free refuges, and a lack of seasonality in predation likely contribute to high regional mortality. Factors that influence quality and quantity of available refuge may ultimately control abundance. Although genetics data describe the population as panmictic, geographic differences in coastal climate and hydrological processes may act to structure populations. Separation of stocks according to ecozones may provide a more suitable approach to population delineation. The 2011 stock assessment divided the population into eastern and western regions based on confounding information on genetics, physiographic features that limit larval transport, variations in climate, and migration of female crabs along the west coast of Florida. There is concern that the population is undergoing Gulf of Mexico-wide changes in biomass associated with regional climate regime shifts that may alter the resiliency of the stock. Whether the shift to a more favorable climate phase would reverse the declining trends is unknown. Changes in population levels could be rapid given the high juvenile mortality and short generation time as well as the importance of climate in structuring habitat.

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“…Inseminated females migrate to the lower estuaries and coastal ocean, where they spawn multiple clutches of 2–5 million zoeae larvae (Prager et al 1990; Hines et al 2003; Darnell et al 2009; Graham et al 2012). Once females complete their spawning migration to high‐salinity waters, they remain in the high‐salinity waters of the lower estuary and coastal ocean (Van Engel 1958; Forward et al 2005; Darnell et al 2012; Kemberling and Darnell 2020). The spawning season in the northern Gulf of Mexico is protracted, with an extended peak in spawning throughout the warm months (April–November) and low‐level spawning occurring year‐round.…”

Section: Introductionmentioning

confidence: 99%

Spatial and temporal variation in exploitation rates of the Louisiana blue crab spawning stock

Olmi‐Graham

Darnell

2023

Trans Am Fish Soc

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Objective Blue crabs Callinectes sapidus support one of our nation's most valuable fisheries, and Louisiana has led national landings from 2012 to 2021. Fishery‐independent estimates of abundance have declined in recent years; in 2015, the Louisiana spawning stock biomass reached the lowest point ever recorded. Management efforts for the blue crab spawning stock have been hindered by incomplete knowledge of the dynamics of natural and fishing mortality. The purpose of this study was to examine spatiotemporal variation in exploitation rates of the Louisiana blue crab spawning stock. Methods From 2016 to 2017, we conducted a mark–recapture study in three Louisiana estuaries. During this period, we tagged 6133 mature female blue crabs, of which 964 were recaptured. Exploitation rate estimates were calculated using recapture data. In 2018, Louisiana implemented a 2‐month female harvest prohibition; to examine impacts of this harvest prohibition on exploitation rates of female blue crabs, we tagged additional females before, during, and after the harvest prohibition. Result Overall exploitation rate estimates for 2016–2017 ranged from 0.27 to 0.30 (i.e., 27–30%), but significant spatial and temporal variation was observed. During 2018, estimated exploitation rate without the harvest prohibition was 0.16–0.18, but with the prohibition, exploitation rate decreased to 0.08–0.09, indicating that this management action was effective in reducing mortality of mature females. Conclusion Nearly one‐third of mature female blue crabs in southeastern Louisiana are captured in the fishery at some point during their life. The 2018 female harvest prohibition reduced exploitation rate of mature females by ~50%. These spatiotemporal estimates of exploitation rate will be directly applicable to future Louisiana blue crab management plans and stock assessments.

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Distribution, relative abundance, and reproductive output of spawning female blue crab (Callinectes sapidus) in offshore waters of the Gulf of Mexico

Cited by 8 publications

References 15 publications

Evidence for Sperm Limitation in the Louisiana Blue Crab Spawning Stock

Evidence for Sperm Limitation in the Louisiana Blue Crab Spawning Stock

Status and Management of the Blue Crab Fishery in the Gulf of Mexico

Spatial and temporal variation in exploitation rates of the Louisiana blue crab spawning stock

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