Biology of the Red Sea Urchin, Strongylocentrotus Franciscanus, and Its Fishery in California

Biology of the Red Sea Urchin, Strongylocentrotus franciscanus, and Its Fishery in California SUSUMU KAT0 and STEPHEN C. SCHROETER Introduction Canada and the United States to answer quested information to help them devel- some of these needs. This report pre- op fisheries for their species of sea Since Kat0 (1972) reported on the sents relevant information from the urchins. beginning of the sea urchin fishery in literature, much of which is not readily California, it has grown dramatically. accessible to persons in the industry, as Description of Sea Urchins The catch has exceeded 11,OOO metric well as from our own investigations. A Sea urchins belong to the phylum tons (t) in 1981 in California, and up to review of red sea urchin, Strongylocen- Echinodermata, which also includes 500 t have been harvested in 1 year in trotus franciscanus (Fig. l), biology is starfish, sea cucumbers, sea lilies, and Washington. Most of the product of the given to promote understanding of brittle stars. All sea urchins have a hard fishery, the roe (both male and female natural processes which can have a calcareous shell called a test, which is gonads), is marketed in Japan, where bearing on the commercial use of sea covered with a thin epithelium and is the sea urchins as well as the roe are urchins. Descriptions of the harvesting, usually armed with spines. The mouth, called “uni.” processing, and marketing sectors of the located on the underside, consists of five Inevitabky, development of the fishery industry are also presented. We hope calcareous plates called “Aristotle’s lan- has raised questions about the status of that this information will aid in main- tern” in honor of the Greek naturalist populations, and effects of the fishery taining a commercially viable and envi- and philosopher. The mouth leads to the on the urchins and environment. Be- ronmentally sound fishery for many digestive tract which empties through cause fishermen, processors, potential years. We hope that this report will fill the anus located on the top of the test. investors, and management officials all the needs of the hundreds of persons Five skeins of roe comprise the most require information, several scientific from throughout the United States as prominent structures in the internal studies were initiated by researchers in well as other countries who have re- cavity of sea urchins. Sea urchins are Susumu Kat0 is with the Tiburon Laboratory, Southwest Fisheries Center, National Marine Fisheries Service, NOAA, Tiburon, CA 94920, and Stephen C. Schrceter is with the Department of Biological Sciences, University of Southern California, University Park, CA 90089. ABSIRACT-The Californiajishery for the red sea urchin, Strongylocentrotus franciscanus, has grown steadily since its inception in 1972, and the mimum annual catch has exceeded 11,000 metric tons. Most of the producr of the jishery, the roe, is exported to Japan, though a significant amount is also consumed in the United Stares. This paper describes aspects of red sea urchin life history, distribution, abundance, ecology, and management. A detailed description of the jshery, including harvesting, processing, shipping, and markering methods, is also Figure 1.-The red sea urchin, Strongylocenrrotusfranciscanus (left), and the given. smaller purple sea urchin, S. purpurarus. 47(3), 1985 I unisexual, being either male or female, constituents are likely to change, de- found as deep as 125 m (McCauley and but cases of hermaphroditism (Le., with pending on the nutritional and reproduc- Carey, 1967). Individuals of both spe- both male and female gonads) have been tive states of the urchins. Sea urchin roe cies prefer rocky substrates, particularly recorded in several species (Boolootian also contains calcium, phosphorus, ledges and crevices (Schrc~ter,1978), and Moore, 1956). Between the skeins iron, Vitamins A, B,, BZ, Bu, nicotinic and avoid sand and mud. of roe are gill-like structures which are acid, pantothenic acid, folic acid, and Both species are often found in and part of the water vascular system, im- carotenes (Higashi et al. 1959, 1965). around stands of the giant kelp, Macro- portant in movement, respiration, and Since polychlorinated biphenols cystis spp., and other brown algae. Typi- food gathering. The gut is dark and (PCB) and other potentially toxic hydro- cally, sea urchins are most abundant often filled with partially digested plant carbons are of major concern to the near the outer edges of kelp beds and material. Japanese, an analysis was undertaken to less numerous inside (Pearse et al., Two species of sea urchins are com- learn the extent of pollution from these 1970; Low, 1975; Pace, 1975; Mattison mon in shallow coastal waters off Cali- noxious compounds. Red sea urchins et al., 1977; Tegner and Dayton, 1981). fornia: The red. S. franciscanus, and collected at Fort Bragg, Calif., in 1973 Adult sea urchins that live within kelp purple, S. purpurufus, sea urchins (Fig. were found to have no detectable beds are larger than those outside, and 1). Several other species also occur in amounts of DIYT, but contained an aver- recent recruits (<lo-20 mm) are much California, but they are either too small age of 0.026 ppm (parts per million of more abundant outside than inside the or too rare to be of economic signifi- wet weight) of DDE (range 0.006-0.050 beds (Pearse et al., 1970; Bernard and cance. In fact, only the red sea urchin ppm). Amounts of PCB averaged 0.04 Miller, 1973; Tegner and Dayton, 1981). is presently harvested, although the pur- pprn and ranged from 0.01 to 0.09 ppml. Similar patterns have been documented ple sea urchin offers potential because Tolerance levels for PCB set by the for green sea urchins, S. drobachiensis) of its abundance. The red sea urchin is Japanese government vary depending on on the coast of Nova Scotia, Canada one of the largest species of sea urchins the foodstuff. In flesh of coastal fishes (Bernstein et al., 1981). Several hypoth- in the world, growing to a test diameter a level of 3.0 ppm is allowed? In the eses have been advanced to account for of about 18 cm. Its test and spine color United States, the maximum allowable these patterns. Individuals within kelp is usually dark purple. Not infrequent- in “shellfish” is 2 ppm. Thus the Cali- beds may be larger either because they ly, however, either the test or spines- fornia sample fell well within acceptable grow faster, survive longer, or both or both-are reddish or light purple. levels. (Pearse et al., 1970). T. A. Ebert’s work The length of the spines may be corre- (1968) supports the conjecture that in- Distribution and Abundance lated with the habitat; sea urchins in dividuals inside are larger because they deeper, calmer waters tend to have Red sea urchins are found on the west have more food. He studied intertidal longer spines than those in shallower coast of North America as far south as populations of purple sea urchins and waters where greater abrasion of spines the tip of Baja California, although their found that the maximum size attained occurs (Silver and Brierton, 1974). The abundance declines south of lat. 27”N by individuals in a population is influ- purple sea urchin, which has relatively (Malagrino Lumare, 1972). They range enced directly by food supply. Addi- short spines, is usually light purple or northward to Sitka and Kodiak, Alaska, tional studies on red sea urchins in lavender. and along the Asiatic coast as far south southern California (Pearse et al., 1970; Sea urchin roe contains an assortment as the southern tip of Hokkaido Island, Baker, 1973) also support this hy- of nutrients. Major components of the Japan (McCauley and Carey, 1967). Off pothesis. roe of red and purple urchins are given the California coast, dense concentra- The much greater abundance of very in Table 1. The percentages of various tions occur patchily throughout the small individuals outside of kelp beds state. Notable exceptions are those areas may be due to higher rates of settlement, off central California where sea otters, higher survival after settlement, or both Enhydra lurris, a major predator of sea (Pearse et al., 1970; Ebert, 1983). High- urchins, are abundant (McLean, 1962; er rates of settlement could result from Table l.-Proximate analyses of red and purple sea urchin me (percent of total roe weight)’. E. E. Ebert, 1968; Lowry and Pearse, active selection by larvae or from the 1973). passive concentration of larvae. Alterna- Red Purple sea urchin sea urchin Both the red sea urchin and its close tively, larvae may be equally abundant ~~ ~~ Item 12 32 relative, the purple sea urchin, usually inside and outside of beds, but may suf- occupy shallow waters, from the mid to fer higher mortality in the former habitat Moisture 700 708 686 71 8 Protein 77 96 95 123 low intertidal zones to depths in excess (Pearse et al., 1970). Lipid 76 83 54 52 of 50 m, but red sea urchins have been Juvenile red sea urchins are frequent- Ash 16 15 13 17 Glycogen 13 17 ly found under the spines of larger red ~ Nonprotein IReuben Lasker, National Marine Fisheries Ser- urchins, and are scarce elsewhere in the nitrogen 01 05 01 05 vice, NOAA, La Jolla, Calif. Personal commun. same habitat (Low, 1975; Breen et al., ‘Sources. 1. Modified alter Greenfield el al , 1958: 2Katsutoshi Miwa, Tokai Regional Fisheries 2 from Krarner and Nordin, 1979: 3 Modified after Research Laboratory, Tokyo, Japan. Personal 1976; Tegner and Dayton, 1977; Schroe- Giese et ai, 1958 commun. ter, 1978). One possible explanation for 2 Marine Fisheries Review this distributional pattern is that larvae et al., 1974; Tegner and Dayton, 1981; along the west coast of North Anicrica.

Load more