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Spawning aggregations of squid (Sepioteuthis australis) populations: a continuum of 'microcohorts'
journal contribution
posted on 2023-05-16, 19:39 authored by Moltschaniwskyj, NA, Gretta PeclGretta PeclThe aim of this study was to determine how size, age, somatic and reproductive condition, abundance and egg production of southern calamary spawning aggregations changed during the spawning season in each of 2 years. During the spawning period in at least one of the years there was a decline as much as 20% in average size, 50% in somatic condition, 28-34% in size-at-age, 26-29% in reproductive status, as well as abundance and reproductive output of the stock declining during the spawning season. However, this change was not a function of the population becoming reproductively exhausted, as the aggregation was composed of different individuals with different biological characteristics. In each month the average age of individuals was ca. 6 mo, indicating that squid that had hatched at different times had entered the spawning aggregations, suggesting that the aggregation was made-up of a succession of microcohorts. Currently, management of many squid populations assumes that there is a single cohort in the aggregation. Therefore, estimating stock biomass at the start of the spawning season cannot be used as the population is constantly changing as micro-cohorts move into the aggregation. An instantaneous estimate of the spawning biomass, independent of fishing activity may be obtained by quantifying the density of deposited eggs. The strategy of individuals with a diversity of life history characteristics coming together in a single spawning aggregation may ensure the phenotypic and genetic diversity required to guarantee successful recruitment of this short-lived species. Therefore, temporally structured protection from harvest throughout the spawning season will ensure maintenance of this population diversity. © Springer Science+Business Media, Inc. 2006.
History
Publication title
Reviews in Fish Biology and FisheriesVolume
17Issue
2-3Pagination
183-195ISSN
0960-3166Department/School
Institute for Marine and Antarctic StudiesPublisher
Springer NetherlandsPlace of publication
NetherlandsRepository Status
- Restricted