References__________________________________________________________________________

Olson AP, Siddon CE, Eckert GL. Spatial variability in size at maturity of golden king crab (Lithodes aequispinus) and implications for fisheries management. R Soc Open Sci. 2018 Mar 7;5(3):171802. doi: 10.1098/rsos.171802.

Abstract. Many crab fisheries around the world are managed by size, sex and season, where males are given at least one opportunity to reproduce before being harvested. Golden king crab (Lithodes aequispinus) supports a commercial fishery in Southeast Alaska and legal size is based on growth and maturity information from other parts of their range. Size-at-maturity estimates varied for crabs among seven management areas in Southeast Alaska, where male maturity estimates increased in size with increases in latitude, while maturity estimates across their North Pacific range decreased in size with increases in latitude. Depth, temperature and harvest history were not related to variation observed in male maturity estimates. Management implications from this research include reducing legal size in some areas to maximize harvest potential and increasing in others to allow male crabs the opportunity to reproduce before being harvested. A more conservative strategy would incorporate the largest maturity estimate, thus increasing the legal size which would have a negative impact to the commercial fishery, but allow male crabs the opportunity to reproduce before being harvested. This study shows the importance of understanding how life-history characteristics change over space and the challenge incorporating spatial variability for improved fisheries management.

Shukalyuk AI, Isaeva VV, Pushchin II, Dolganov SM. Effects of the Briarosaccus callosus infestation on the commercial golden king crab Lithodes aequispina. J Parasitol. 2005 Dec;91(6):1502-4. doi: 10.1645/GE-489R1.1.

Abstract. Commercial crab populations off the Kamchatka coasts are infested to a considerable degree by the rhizocephalan parasite Briarosaccus callosus: of 769 Lithodes aequispina males examined, 43 (5.7%) were parasitized. Infestations result in the feminization of the crabs, a significant decrease in the cheliped length, and a significant decrease in the carapace length and width. We suggest that commercial selection of healthy males, and the returning of unsuitable crabs, including infested ones, back into the sea, results in an increase of the proportion of infested crabs in the population, their elimination from reproduction, and, eventually, the gradual degradation of a whole population. To minimize as far as possible the negative effects of commercial crab harvesting, all infested crab specimens caught must be destroyed, either aboard or elsewhere, instead of throwing them back into the sea.

Olson, A. 2023 Recommended Harvest Strategy for Southeast Alaska Golden King Crab (Lithodes aequispinus).

BACKGROUND . The Alaska Department of Fish and Game (department) golden king crab (Lithodes aequispinus, GKC) fishery in Southeast  Alaska is a data-limited fishery that is managed based on a 3-S management system (sex, size, and season). The management system has been further developed by limiting the number of participants and gear, establishing guideline harvest levels (GHLs) that are set within guideline harvest ranges (GHRs) for each management area (Table 1), and closing of management areas if there are stock health concerns. The majority of GKC harvest occurs in the commercial sector where the fishery extends across seven management areas (Northern, Icy Strait, North Stephens Passage, East Central, Mid-Chatham Strait, Lower Chatham Strait, and Southern). The department annually evaluates stock status and establishes GHLs for each management area using fishery dependent data (Stratman et al. 2017; Olson et al. 2018). Management area GHRs were examined in 2015 for their biological relevance due to declines in fishery performance and results were used in establishing current GHRs since 2018 (K. Palof and A. Olson, 2017, unpublished data). The goal of this analysis was to establish a biological-based maximum sustainable yield (MSY) from historical fisheries catch and effort data using biomass dynamic models. Biomass dynamic models are a simple fisheries model that applies basic population dynamics to harvest data. They are not ideal models for most assessments and management due to their manyassumptions and caveats; however, they are useful because the only data needed is a time series of harvest and an index of abundance, which is generally fishery catch per unit of effort (CPUE). These models assume that catch is related to available biomass, meaning that harvest is not limited by GHLs or number of days. Another major assumption is that the population remains in a similar “state of growth” during the entire time period. There is only one parameter estimated for growth of the population, or production of the population, this parameter incorporates all aspects of production – recruitment, growth of individuals, and mortality. When many of the assumptions are not met these models are considered non-conservative and often provide over inflated estimates of MSY. Because of this, the MSY estimates obtained from these models are treated as an upper limit (i.e., upper end of the GHR) of sustainable harvest for each area. A GHL is a preseason estimated level of allowable harvest that will not jeopardize the sustained yield of the stock. 

Stevens, B. G., Dunham, A., Kittaka, J., Kovatcheva, N. P., Persselin, S., & van der Meeren, G. I. (2014). Aquaculture and stock enhancement of king crabs. King crabs of the world: biology and fisheries management, 403-448.

Abstract. Populations of red king crab (RKC) Paralithodes camtschaticus (Tilesius, 1815) and blue king crab (BKC) P. platypus in Alaska have uctuated greatly over the last three decades (Chilton et al., 2011). After peak landings in 1980, the RKC sheries in the Bering Sea and Kodiak, Alaska, were closed in 1983. Although the Bering Sea shery reopened in 1984, the shery in Kodiak, Alaska, has never been reopened due to low population abundance. Other commercial sheries in the Bering Sea, including snow crab (Chionoecetes opilio) and Tanner crab (C. bairdi) are considered to be over-shed, and the latter has been closed since 1996. At the Pribilof Islands, BKC shery was closed from 1988 to 1994 and reopened in 1995; both sheries were closed in 1998 (NPFMC, 2002). The shery at St.  Matthew Island reopened in 2010, but the Pribilof Islands shery remained closed. Simultaneously, the population of RKC in the Pribilof Islands has increased since 1991, but no directed shing for RKC has occurred there since 1998 in order to prevent the bycatch of BKC. Although there is great uncertainty about the ultimate cause of recruitment variability (Blau, 1986), many hypotheses have been proposed, including egg predation (Kuris et al., 1991), disease, overshing (Orensanz et al., 1998), bycatch (Dew and McConnaughey, 2005), and climatic changes (Zheng and Kruse, 2000). Changes in spatial distribution associated with climate variability may also be involved (Loher and Armstrong, 2005), but the linkage between environmental change and population abundance is not yet understood.