662 



Abstract— Commercial hai-vest of red 

 sea urchins began in Washington state 

 in 1971. Harvests peaked in the late 

 1980s and have since declined substan- 

 tially in Washington and other areas of 

 the U.S. west coast. We studied effects 

 of experimental hai-vest on red sea 

 urchins in San Juan Channel (SJC), a 

 marine reserve in northern Washing- 

 ton. We recorded changes in density 

 and size distribution of sea urchin 

 populations resulting from three levels 

 of experimental harvest: 1) annual 

 size-selective harvest (simulating cur- 

 rent commercial urchin harvest regula- 

 tions), 2) monthly complete (non-size- 

 selective) harvest, and 3 1 no harvest 

 I control I sites. We also examined re- 

 colonization rates of harvested sites. 

 The red sea urchin population in SJC is 

 composed of an accumulation of large, 

 old individuals. Juvenile urchins rep- 

 resent less than 1% of the population. 

 Lower and upper size limits for com- 

 mercial hai"vest protect 5'7r and 4.5'* of 

 the population, respectively. Complete 

 harvest reduced sea urchin densities 

 by SS'i. Annual size-selective harvest 

 significantly decreased sea urchin 

 densities by 67% in the first year and 

 by 47% in the second year. Two years 

 of size-selective harvest significantly 

 altered the size distribution of urchins, 

 decreasing the density of legal-size 

 urchins. Recolonization of harvested 

 sites varied seasonally and occurred 

 primarily through immigj"ation of 

 adults. Selective harvest sites were 

 recolonized to 51% and 38% of original 

 densities, respectively, six months after 

 the first and second annual harvests. 

 Yields declined substantially in the 

 second year of size-selective harvest 

 because of the fishing down of the 

 population and because of low recoloni- 

 zation rates of harvested sites. We 

 recommend that managers consider 

 the potential efficacy of marine hai-vest 

 refuges and reevaluate the existing 

 upper and lower size limits for com- 

 mercial harvest to improve long-term 

 management of the sea urchin fishery 

 in Washington. 



Effects of experimental harvest on 



red sea urchins iStrongylocentrotus franciscanus) 



In northern Washington 



Sarah K. Carter 

 Glenn R. VanBlaricom 



Washington Cooperative Fish and Wildlife Research Unit 



School of Aquatic and Fishery Sciences 



Box 355020 



University ol Washington 



Seattle, Washington 98195 5020 



Present address (for S K. Carter); Wisconsin Department of Natural Resources 



Bureau of Endangered Resources 



tOl South Webster St 



Madison. Wisconsin 53707-7921 

 E mail address (for S K Carter) carteskm^dnrstate wi us 



Manuscript accepted 28 March 2002. 

 Fish. Bull. 100:662-673 (2002). 



Red sea urchins iSti-ongyloccntrotus 

 franciscanus) are the most commonly 

 harvested species of sea urchin on the 

 west coast of North America. Sea urchin 

 harvest in this region occurs primarily 

 in California, Washington, and British 

 Columbia. The commercial sea urchin 

 fishery in Washington began in 1971, 

 and landings were low through the 

 early 1980s (Fig. 1). Landings increased 

 dramatically in the late 1980s, peaking 

 at over 4000 metric tons (t) in 1988. 

 Landings have since declined. Approxi- 

 mately 387 t of sea urchins were har- 

 vested in 2000, valued at $699,052 

 ( LTlrich' I. Red sea urchins currently con- 

 stitute approximately 60% of landings — 

 the remainder being green sea urchins 

 (S. droebachiensis. UlrichM. 



The Washington sea urchin fishery 

 currently is managed by using harvest 

 quotas, size limits, license restrictions, 

 limited entry, and mandatory log books 

 (Lai and Bradbury, 1998). Season length 

 is not limited, but haivest occurs pri- 

 marily during the winter when roe qual- 

 ity is highest (Bradbury^). A rotational 

 harvest strategy was practiced from 

 1977 until 1995, in which each harvest 

 district ( Fig. 2 ) was hai-vested once every 

 third year. In 1995 a U.S. federal court 

 ruling on shellfishery management in 

 Washington's coastal marine waters 

 (Shellfish Subproceedings of United 

 States vs. State of Washington, 873 F. 

 suppl. 1422, 1994, known commonly as 

 the "Rafeedie Decision") allotted one 

 half of all hai-vestable shellfish to native 



tribes. As a result, rotational harvest 

 was discontinued and replaced by an- 

 nual harvest to ensure that all tribes 

 had equal access to their usual and ac- 

 customed fishing areas each year. 



Sea urchin harvests declined sub- 

 stantially in the early 1990s along 

 parts of the west coast (Fig. 1). Quotas 

 and season lengths were reduced in 

 Washington because of overharvest- 

 ing concerns (Bradbury-). Quotas were 

 not reduced in California, and catches 

 declined substantially (Kalvass and 

 Hendrix, 1997). Sea urchin densities 

 in some harvested areas in northern 

 California are less than one quarter of 

 those in nearby reserve areas (Kalvass 

 and Hendrix, 1997). In Washington, 

 densities and the proportion of legal- 

 size sea urchins in the population 

 have declined (Pfister and Bradbury, 

 1996). Harvesters may be maintaining 

 catch per unit of effort at high levels 

 by exploiting new populations, thereby 

 masking stock declines (Pfister and 

 Bradbury, 1996). 



Experimental hai-vests may indicate 

 potential effects of commercial harvest 



' Ulrich.M. 2001. Personal commun. Wash- 

 ington State Department of Fish and 

 Wildlife, 600 Capitol Wav North, Olympia, 

 WA 98.501. 



- Bradbury, A. 2000. Personal commun. 

 Washington State Department of Fish and 

 Wildlife. Point Whitney Shellfish Labora- 

 tory. 1000 Point Whitnev Road, Brinnon, 

 WA 98320. 



