. Bulletin. Science; Natural history; Natural history. 10000 8000 137 eooo fn 4000 2000 Sicyonia ingentis 6000 4000 2000 Pleuroncodes planipes A 78 80 82 84 86 78 80 82 84 86. Fig. 10. Representative invertebrates trawled off Palos Verdes, 1978 to 1992. Catch is mean of quarterly 10-minute trawls at 4 sites (TO, Tl, T4, T5) at indicated depth (23-, 61- or 137-m). taxa were Sicyonia ingentis (ridgeback rock shrimp, 40% of the 15-year inverte- brate catch), Lytechinus pictus (white sea urchin, 30%), and Pleuroncodes planipes (pelagic red crab, 25%). Echinoderms were the most numerous in the 1990
. Bulletin. Science; Natural history; Natural history. 10000 8000 137 eooo fn 4000 2000 Sicyonia ingentis 6000 4000 2000 Pleuroncodes planipes A 78 80 82 84 86 78 80 82 84 86. Fig. 10. Representative invertebrates trawled off Palos Verdes, 1978 to 1992. Catch is mean of quarterly 10-minute trawls at 4 sites (TO, Tl, T4, T5) at indicated depth (23-, 61- or 137-m). taxa were Sicyonia ingentis (ridgeback rock shrimp, 40% of the 15-year inverte- brate catch), Lytechinus pictus (white sea urchin, 30%), and Pleuroncodes planipes (pelagic red crab, 25%). Echinoderms were the most numerous in the 1990s, with smallest populations in 1984 and 1985 (Fig. 9). Representative species are plotted in Fig. 10. Lytechinus pictus (white sea urchin) dominated shelf (23- and 61-m) catches, especially near the Redondo Canyon (TO). Since the late 1980s, large populations also occur across the entire 23-m isobath, including inshore of the outfalls. Smallest 23-m catches were taken after storms. Allocentrotus fragilis (fragile sea urchin) was common on the upper slope (T1-137; T5-137 from the late 1980s) except during and following the El Nino and storms. Fewer were taken near the outfall (T4- 137). Astropecten verrilli (California sand star) was most common on the shelf (TO-, T4- and T5-61), and in 1982; fewest were caught after El Niiios (1978 and 1984). Arthropods increased markedly in 1983, flourished in 1984 and 1985, and declined from 1986 (Fig. 9). Representative species are plotted in Fig. 10. Sicyonia ingentis (ridgeback rock shrimp) was very abundant on the upper slope (especially TO- and T5-137) from 1983-1986, following El Nino. Pleuroncodes planipes (pe- lagic red crab) was abundant in 1984 and 1985, particularly in the upper slope outfall area (T4-137). Pandalus jordani (a northern ocean shrimp) was common by Redondo Canyon (TO-137), 1978 to 1982. It declined following the 1982 to 1983 El Nino and did not return. Portunus xantusii (Xantus swimming crab) was abundant on the inn
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