Predation Scars Reveal Declines in Crab Populations Since the Pleistocene

Kristina M Barclay,Lindsey R Leighton

doi:10.3389/fevo.2022.810069

Kristina M Barclay, Lindsey R Leighton

Open Access

https://doi.org/10.3389/fevo.2022.810069

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Abstract

Despite growing concerns over global fisheries, the stock status of most commercially exploited species are poorly understood. Fossil data provide pre-anthropogenic baselines for data-poor fisheries, yet are underutilized in fisheries management. Here, we provide the first use of predation traces to assess the status of fisheries (crab). We compared crab predation traces on living individuals of the crab prey gastropod, Tegula funebralis, to Pleistocene individuals from the same regions in southern California. There were fewer crab predation traces on modern gastropods than their Pleistocene counterparts, revealing reductions in crab abundances today compared to the Pleistocene. We conclude that: (1) regardless of the cause, immediate actions are required to avoid further population reductions of commercially exploited crabs in southern California, (2) predation traces are a rapid, cost-effective method to assess otherwise data-poor fisheries, and (3) the inclusion of fossil data provides key new insights for modern resource and fisheries management.

Highlights

Fisheries management is vital to ensure the sustainability of fisheries in the face of continued climate change and overfishing (Harley et al, 2006; Allison et al, 2009; Ekstrom et al, 2015), for vulnerable coastal communities that are reliant on marine resources (Dolan and Walker, 2006; Cinner et al, 2012; Whitney and Ban, 2019)
Given that the shell-crushing crab taxa are similar between the Pleistocene and modern, and that it is unknown if repair scars allow differentiation between species of cancrid crabs, it is assumed that repair scars represent an overall cancrid crab signal that should appear similar between the Pleistocene and modern of southern California
Our results demonstrate a decrease in repair frequencies in modern compared to Pleistocene assemblages, conservatively indicating fewer crab attacks today compared to the Pleistocene

Summary

Introduction

Fisheries management is vital to ensure the sustainability of fisheries in the face of continued climate change and overfishing (Harley et al, 2006; Allison et al, 2009; Ekstrom et al, 2015), for vulnerable coastal communities that are reliant on marine resources (Dolan and Walker, 2006; Cinner et al, 2012; Whitney and Ban, 2019). First-hand accounts suggest that overfishing is already affecting multispecies rock crab populations and body sizes in southern California (Fitzgerald et al, 2018, 2019) Management of these fisheries is hampered by a lack of data other than gross landings (Culver et al, 2010; NOAA Fisheries Landings, 2019). Cancrids from the Pleistocene of southern California are known mostly from occasional chela (claws), which preserve more readily than the rest of the body (Menzies, 1951; Nations, 1975) Pleistocene species and their distributions are comparable to the present, consisting of the same major cancrid taxa, including Cancer productus, Metacarcinus anthonyi, M. gracilis, M. magister, Romaleon antennarium, and R. branneri (Menzies, 1951; Nations, 1975). Faced with a lack of current or historical data, limited fisheries management resources, and a generally poor body fossil record of crabs, alternative evidence is needed to guide the management of current crab stocks

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