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Changes in catch rates and length and age at maturity, but not growth, of an estuarine plotosid (Cnidoglanis macrocephalus) after heavy fishing
Citation
Chuwen, BM and Potter, IC and Hall, NG and Hoeksema, SD and Laurenson, LJB, Changes in catch rates and length and age at maturity, but not growth, of an estuarine plotosid (Cnidoglanis macrocephalus) after heavy fishing, Fishery Bulletin, 109, (3) pp. 247-260. ISSN 0090-0656 (2011) [Refereed Article]
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Abstract
The hypothesis that heavy
fishing pressure has led to changes
in the biological characteristics of the
estuary cobbler (Cnidoglanis macrocephalus)
was tested in a large seasonally
open estuary in southwestern
Australia, where this species completes
its life cycle and is the most
valuable commercial fish species.
Comparisons were made between
seasonal data collected for this plotosid
(eeltail catfish) in Wilson Inlet
during 2005¨C08 and those recorded
with the same fishery-independent
sampling regime during 1987¨C89.
These comparisons show that the
proportions of larger and older individuals
and the catch rates in the
more recent period were far lower,
i.e., they constituted reductions of
40% for fish ¡Ý430 mm total length,
62% for fish ¡Ý4 years of age, and 80%
for catch rate. In addition, total mortality
and fishing-induced mortality
estimates increased by factors of ~2
and 2.5, respectively. The indications
that the abundance and proportion
of older C. macrocephalus declined
between the two periods are consistent
with the perception of long-term
commercial fishermen and their shift
toward using a smaller maximum gill
net mesh to target this species. The
sustained heavy fishing pressure on
C. macrocephalus between 1987¨C89
and 2005¨C08 was accompanied by a
marked reduction in length and age
at maturity of this species. The shift
in probabilistic maturation reaction
norms toward smaller fish in 2005¨C08
and the lack of a conspicuous change
in growth between the two periods
indicate that the maturity changes
were related to fishery-induced evolution
rather than to compensatory
responses to reduced fish densities.
Item Details
| Item Type: | Refereed Article |
|---|---|
| Research Division: | Agricultural, Veterinary and Food Sciences |
| Research Group: | Fisheries sciences |
| Research Field: | Aquaculture |
| Objective Division: | Animal Production and Animal Primary Products |
| Objective Group: | Fisheries - wild caught |
| Objective Field: | Fisheries - recreational freshwater |
| UTAS Author: | Chuwen, BM (Dr Ben Chuwen) |
| ID Code: | 71832 |
| Year Published: | 2011 |
| Web of Science® Times Cited: | 17 |
| Deposited By: | Sustainable Marine Research Collaboration |
| Deposited On: | 2011-08-10 |
| Last Modified: | 2014-09-05 |
| Downloads: | 514 View Download Statistics |
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