Effects of commercial fishing on the population structure of spawning southern calamary (Sepioteuthis australis) |
| |
Authors: | Ty Hibberd Gretta T Pecl |
| |
Institution: | (1) Institute of Antarctic and Southern Ocean Studies, University of Tasmania, Private Bag 77, Tasmania, Hobart, 7001, Australia;(2) Tasmanian Aquaculture and Fisheries Institute, University of Tasmania, Private Bag 49, Tasmania, Hobart, 7001, Australia |
| |
Abstract: | This study explored population dynamics of Sepioteuthis australis on a fine temporal scale before, during, and after a 3-month commercial fishing closure on the summer inshore spawning grounds
of Great Oyster Bay, Tasmania, Australia. An abrupt change in male size (mantle length) and population sex ratio after the
re-opening of the commercial fishery suggests that fishing alters the population structure on the spawning beds from a ‘natural’
structure which is highly biased towards males, to a more even ratio of males to females. Although jigs are taking a representative
sample of the squid population using the spawning beds at any one time, the fishery is apparently still effectively selective
for males, potentially as a function of differential spawning movements of the two sexes. Increased fishing pressure over
the past 5 years had been correlated with a change towards a highly male-biased sex ratio on the spawning beds; however the
current study suggests that increased fishing pressure in recent years may not have reduced the proportion of females. Instead,
the inter-annual change in sex ratio may reflect changes in the degree of protection from fishing, with progressively longer
closures allowing time for more males to accumulate on the beds and therefore, for the proportion of males to increase (as
opposed to a decrease of females). As fishing is selective for males, fishing throughout the spawning season could potentially
modify the process of sexual selection and the mating behaviors of the individuals within the spawning population, highlighting
the need for closures over this crucial period. Additionally, examinations and comparisons of squid population structure need
to be interpreted in light of fishing pressure and broader movement patterns. |
| |
Keywords: | Sex ratio Commercial closure Fishing pressure Population structure Squid Spawning aggregation |
本文献已被 SpringerLink 等数据库收录! |
|