Teck SJ et al. (2018), Quality of a fished resource: Assessing spatial...

ECB-ART-46391

PLoS One 2018 Jan 01;136:e0196864. doi: 10.1371/journal.pone.0196864.

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Quality of a fished resource: Assessing spatial and temporal dynamics.

Teck SJ , Lorda J , Shears NT , Ben-Horin T , Toseland RE , Rathbone ST , Rudie D , Gaines SD .

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Understanding spatio-temporal variability in the demography of harvested species is essential to improve sustainability, especially if there is large geographic variation in demography. Reproductive patterns commonly vary spatially, which is particularly important for management of "roe"-based fisheries, since profits depend on both the number and reproductive condition of individuals. The red sea urchin, Mesocentrotus franciscanus, is harvested in California for its roe (gonad), which is sold to domestic and international sushi markets. The primary driver of price within this multi-million-dollar industry is gonad quality. A relatively simple measure of the fraction of the body mass that is gonad, the gonadosomatic index (GSI), provides important insight into the ecological and environmental factors associated with variability in reproductive quality, and hence value within the industry. We identified the seasonality of the reproductive cycle and determined whether it varied within a heavily fished region. We found that fishermen were predictable both temporally and spatially in collecting urchins according to the reproductive dynamics of urchins. We demonstrated the use of red sea urchin GSI as a simple, quantitative tool to predict quality, effort, landings, price, and value of the fishery. We found that current management is not effectively realizing some objectives for the southern California fishery, since the reproductive cycle does not match the cycle in northern California, where these management guidelines were originally shaped. Although regulations may not be meeting initial management goals, the scheme may in fact provide conservation benefits by curtailing effort during part of the high-quality fishing season right before spawning.

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Genes referenced: LOC100887844 LOC100893907 LOC105443172 LOC115925415 LOC582258

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	Fig 1. Map of the Northern Channel Islands.Map of the Santa Barbara Channel with California Department of Fish and Wildlife (CDFW) 10 x 10 nautical mile fishing blocks surrounding the northern Channel Islands from west to east: San Miguel Island (SMI), Santa Rosa Island (SRI), Santa Cruz Island (SCI), and Anacapa Island (AI). All subregions include 4 CDFW 10 x 10 nautical mile blocks, except Anacapa only includes 2 blocks: west includes all of SMI and the western tip of SRI, central includes the majority of SRI and the western tip of SCI, east includes the majority of SCI, and Anacapa includes the entire island of Anacapa. Marine reserves are outlined in black.
	Fig 2. Red sea urchin seasonal reproductive cycle.Monthly mean gonadosomatic index per boat sampled from red sea urchins landed at the port of Santa Barbara from December 2008 to December 2011 per island: San Miguel Island (SMI), Santa Rosa Island (SRI), and Santa Cruz Island (SCI); error bars show one standard error. Lines show the quartic polynomial fits for viewing purposes only of the monthly means per island. The gray box highlights the months when fishing is limited to four-days per week.
	Fig 3. Processor quality index, price, and gonadosomatic index.Processor data regressions: (a) mean port-sampling gonadosomatic index (GSI) predicting mean processor quality index (PQI) and (b) mean PQI predicting mean processor price per kg (USD). Error bars show one standard error.
	Fig 4. Red sea urchin monthly commercial fishing.Monthly data from California Department of Fish and Wildlife (CDFW) in commercial red sea urchin (a) total effort (number of receipts), (b) total landings (thousands of kg), (c) mean price per kg ± one SE (USD), and (d) total value (thousands of USD) for the northern Channel Islands fishery per year (2009–2011) within the four subregions (see Fig 1). (Note: Anacapa was excluded from plot (c) mean price per kg due to extreme outliers and since less than 1% of the receipts, landings, and value came from Anacapa.) The gray box highlights the months when fishing is limited to four-days per week. Summary statistics are provided in Table 1.
	Fig 5. Predicting red sea urchin fishing from gonadosomatic index.Mean port-sampling gonadosomatic index (GSI) predicting average monthly California Department of Fish and Wildlife (CDFW) data for 2009–2011 and for 1978–2008 in (a, e) effort (number of receipts), (b, f) total landings (millions of kg), (c, g) mean price per kg (USD), (d, h) total value (millions of USD) within the west subregion (see Fig 1). Error bars show one standard error (note: many error bars are smaller than marker size).
	Fig 6. Regional comparison of the california sea urchin fishery.Comparing months across the California sea urchin fishery within Fort Bragg in northern California and the Channel Islands in southern California. Gray highlights: (a) the five months with limited fishing across the state of California (commercial sea urchin fishermen are allowed to fish four-days per week during these months); the rest of the year there is unlimited fishing; (b) the six months with the lowest quality (yield) from a processor in Fort Bragg 1991–1992 (Table B in S3 Appendix), the location and time-frame which was examined to establish the four-day work weeks; July is excluded due to the fishery being closed during this period; (c) the six months with the lowest prices in Fort Bragg 1991–1992 (Table C in S3 Appendix); (d) the four months with the lowest prices in Fort Bragg 2002–2011 (Table D in S3 Appendix), (e) the six months with the lowest prices in the Channel Islands 2002–2011 (Table E in S3 Appendix); (f) the six months with the lowest quality gonadosomatic index (GSI) in the Channel Islands 2009–2011 (Table B in S2 Appendix) and (g) the five months with the highest spawning levels in the Channel Islands 2009-2011(Table A in S3 Appendix).

References [+] :

Arafa, The influence of season on the gonad index and biochemical composition of the sea urchin Paracentrotus lividus from the Golf of Tunis. 2012, Pubmed, Echinobase