Evidence for Sperm Limitation in the Louisiana Blue Crab Spawning Stock

Abstract

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.

Short‐term fishery gains mask long‐term resource pains: Spatial fisheries management changes promote hyperstable CPUE in Labrador snow crab Chionoecetes opilio during a period of heavy exploitation

“…Sperm limitation as a biological response to overexploitation is not a new phenomenon for crustaceans. Although this is the first time that it has been documented in snow crab, sperm limitation due to the selective harvest and overexploitation of large male crabs has been noted in U.S. fisheries for blue crab Callinectes sapidus (Ogburn et al 2019; Olmi‐Graham and Darnell 2022). In the case of AD 2HJ, reproductive capacity concerns extend beyond localized scales because this area lies at the northernmost limit of the stock range, and southerly flowing currents are known to deliver larvae of numerous species from Labrador into downstream areas (Le Corre et al 2019).…”