267 
Abstract .—The concept that de- 
pleted populations of marine fishes can 
be revitalized by releasing cultured fish 
is being tested in Hawaii. In this study 
we evaluated effects of interaction be- 
tween release season and size-at-re- 
lease on recapture rates of cultured 
striped mullet, Mugil cephalus, re- 
leased into Kaneohe Bay, Hawaii. Over 
90,000 cultured M. cephalus finger- 
lings, ranging in size from 45 to 130 mm 
total length, were tagged with binary 
coded-wire tags. Half were released in 
spring, the remainder in summer. In 
both seasons, releases were made in 
three replicate lots. In each replicate, 
five size intervals of fish were released 
at two nursery habitats in Kaneohe 
Bay. Monthly cast-net collections were 
made in 6 nursery habitats over a 45- 
week period to monitor recapture rates, 
growth, and dispersal of cultured fish. 
Recapture rate was directly affected 
by the seasonal timing of releases. 
Greatest recovery of the smallest fish 
released (individuals <60 mm) occurred 
following spring releases and coincided 
with peak recruitment of similar-size 
wildM. cephalus juveniles. In contrast, 
recovery of fish that were <60 mm at 
release was very poor after summer 
releases. Overall survival was similar 
at both release sites. We hypothesize 
that survival of released cultured fish 
will be greater when releases are timed 
so that fish size-at-release coincides 
with modes in the size structure of wild 
stocks. To optimize effectiveness of 
stock enhancement as a fishery-man- 
agement tool, pilot release-recapture 
experiments should be conducted to 
evaluate effects of release season on 
size-dependent recovery of released 
animals. 
Manuscript accepted 9 September 1996. 
Fishery Bulletin 95:267-279 (1997). 
Influence of release season on 
size-dependent survival of cultured 
striped mullet, Mugil cephalus, 
in a Hawaiian estuary 
Kenneth M. Leber 
The Oceanic Institute 
Makapuu Point, Waimanalo, Hawaii 96795 
Present Address: Mote Marine Laboratory 
1 600 Ken Thompson Parkway, Sarasota, Florida 34236 
E-mail address: KLeber@marinelab.sarasota.fl.as 
H. Lee BSankenship 
Steve M. Arce 
Washington Department of Fish and Wildlife 
600 Capitol Way North, Mail Stop 43 1 35 
Olympia, Washington 98501-1091 
Nathan R Brennan 
Tennessee Cooperative Fishery-Research Unit 
Tennessee Technological University 
PO. Box 5144, Cookeville, Tennessee 38505 
With world fisheries yields in steady 
decline (FAO, 1992, 1994; WRI, 
1996), renewed interest in stock 
enhancement based on marine 
hatchery-releases is growing world- 
wide. This interest follows the dem- 
onstrated impact of stock enhance- 
ment in freshwater systems (e.g. 
Foerster, 1936; Solazzi et al., 1991) 
and is coupled with rapidly expand- 
ing marine aquaculture technology 
(Colura et al., 1976; Roberts et al., 
1978; 0iestad et al., 1985; Lee and 
Tamaru, 1988; Eda et al., 1990; 
Fores et al., 1990; Tilseth and Blom, 
1992; Honma, 1993; Main and 
Rosenfeld, 1994; Ostrowski et al., 
1996). 
An experimental and careful ap- 
proach is needed to ensure that 
hatchery releases in marine sys- 
tems result, at best, in successful 
supplementation or replenishment 
of marine fish populations, or, at 
least, in a better understanding of 
system uncertainty (Peterman, 
1991; Blankenship and Leber, 
1995). This approach should involve 
an initial research phase with pilot 
releases to explore the effectiveness 
of release strategies. Before initiat- 
ing a test release to evaluate stock- 
enhancement potential in Hawaiian 
coastal environments, initial re- 
search was focused on a series of 
release experiments to determine 
which release strategies yielded 
greater survival of hatchery fish in 
the wild. This approach provided a 
more powerful field test of the ma- 
rine stock-enhancement concept by 
using prior knowledge about the 
effects of 1) fish size-at-release, 2) 
release habitat, and 3) release sea- 
son on growth and survival (Cowx, 
1994; Blankenship and Leber, 1995; 
Leber et al., 1996). 
Evidence is mounting that release 
habitat, season, and size-at-release, 
can substantially affect success of 
marine hatchery releases (e.g. 
Tsukamoto et al., 1989; Svasand 
