The decline and recovery of four predatory fishes from the Southern California Bight

ISSN： 0025-3162

Source： Marine Biology, Vol.154, Iss.2, 2008-04, pp. : 307-313

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Abstract

What to do about fisheries collapse and the decline of large fishes in marine ecosystems is a critical debate on a global scale. To address one aspect of this debate, a major fisheries management action, the removal of gill nets in 1994 from the nearshore arena in the Southern California Bight (34°26′30″N, 120°27′09″W to 33°32′03″N, 117°07′28″W) was analyzed. First, the impetus for the gill net ban was the crash of the commercial fishery for white seabass (Atractoscion nobilis; Sciaenidae) in the early 1980s. From 1982 to 1997 catch remained at a historically low level (47.8 ± 3.0 mt) when compared to landings from 1936–1981, but increased significantly from 1995–2004 (r = 0.89, P < 0.01) to="" within="" the="" 95%="" confidence="" limit="" of="" the="" historic="" california="" landings.="" after="" the="" white="" seabass="" fishery="" crashed="" in="" the="" early="" 1980s,="" landings="" of="" soupfin="">Galeorhinus galeus; Triakidae) and leopard shark (Triakis semifasciata; Triakidae) also significantly declined (r = 0.95, P < 0.01 and="">r = 0.91, P < 0.01, respectively)="" until="" the="" gill="" net="" closure.="" after="" the="" closure="" both="" soupfin="" and="" leopard="" shark="" significantly="" increased="" in="" cpue="">r = 0.72, P = 0.02 and r = 0.87, P < 0.01, respectively).="" finally,="" giant="" sea="" bass="">Stereolepis gigas; Polyprionidae) the apex predatory fish in this ecosystem, which was protected from commercial and recreational fishing in 1981, were not observed in a quarterly scientific SCUBA monitoring program from 1974 to 2001 but reappeared in 2002–2004. In addition, CPUE of giant seabass increased significantly from 1995 to 2004 (r = 0.82, P < 0.01) in="" the="" gill="" net="" monitoring="" program.="" the="" trends="" in="" abundance="" of="" these="" fishes="" return="" were="" not="" correlated="" with="" sea="" surface="" temperature="" (sst),="" the="" pacific="" decadal="" oscillation="" (pdo)="" or="" the="" el="" niño/southern="" oscillation="" (enso).="" all="" four="" species="" increased="" significantly="" in="" either="" commercial="" catch,="" cpue,="" or="" in="" the="" scuba="" monitoring="" program="" after="" the="" 1994="" gill="" net="" closure,="" whereas="" they="" had="" declined="" significantly,="" crashed,="" or="" were="" absent="" prior="" to="" this="" action.="" this="" suggests="" that="" removing="" gill="" nets="" from="" coastal="" ecosystems="" has="" a="" positive="" impact="" on="" large="" marine="" fishes.="">