Reproductive biology of the Australian herring Arripis georgiana

Abstract

Arripis georgiana was collected from along the Western Australian and South Australian coasts at regular intervals between October 1996 and December 1998. The trends exhibited during the year by gonadosomatic indices, gonadal maturity stages and oocyte stages demonstrate that spawning is restricted to south-western Australian waters from at least as far north as ~28˚43′S to as far east as ~119˚24′E, and that it occurs mainly during late May and early June. The simultaneous presence of post-ovulatory follicles and hydrated and yolk-granule oocytes in some ovaries during the spawning period indicates that A. georgiana is a multiple spawner, i.e. females spawn more than once in a breeding season. In south-western Australia, where all life-cycle stages are found, the overall sex ratio in catches collected by netting was close to parity, whereas females predominated in those obtained by anglers. The length at which 50% of fish reached maturity was 197 mm for females and 179 mm for males, and just over 50% of females and ~80% of males attained maturity at the end of their second year of life. The implications of these data for management of the fishery for A. georgiana are discussed.

Stock structure of Australian herring (Arripis georgiana) in southwestern Australia

“…The timing of this migration corresponds to the period of spawning activity between Perth (lower west coast) and Bremer Bay (western south coast) (Fairclough et al, 2000a). Both the low proportion of recaptures from the lower west and eastern south coast regions, of fish originally tagged on the western south coast, and the lack of movement of fish tagged in Geographe Bay to other regions, suggest an overall westward migration along the south coast of Western Australia, with the lower west coast population exhibiting limited movement.…”

Implications of the divergent use of a suite of estuaries by two exploited marine fish species

“…These species were also caught previously at the same sites in the Broke, Irwin and Wilson Inlets in the last month of winter and spring of 2005 and in the Wellstead Estuary in spring 2005. Additional samples of A. georgianus were also obtained from commercial gillnet fishers operating in Wilson Inlet during April and June of 2006, 2007 and 2010, and thus in the months either side of that in which the spawning of this species peaks in coastal marine waters (Fairclough et al , 2000 a ). These samples were used specifically for histology to provide supplementary data on the gonadal stages and oocyte characteristics of A. georgianus in those months.…”

“…The gonads of each fish were identified macroscopically as either ovaries or testes, or as indeterminate in the case of the smallest fishes with very small gonads that could not be sexed. The macroscopic characteristics of the gonads of each female of A. georgianus were used to assign each gonad to one of the following stages of gonadal development according to the macroscopic criteria described by Fairclough et al (2000 a ) on the basis of the gonadal development of this species in marine waters. I = virgin, II = maturing virgin/resting adult, III = developing, IV = partially developed, V = prespawning, VI = spawning, VII = spent and VIII = recovering spent.…”

“…28° 40′ S and eastwards to c . 119° 25′ E in Western Australia and mainly during the very short period of late May and early June (Fairclough et al , 2000 a ). Many of the resultant larvae and juveniles that are produced on the lower west coast and more particularly on the south coast are transported eastwards to nursery areas on the eastern south coast of Western Australia and in South Australia by the flow of the Leeuwin Current and wind‐driven easterly movements of coastal waters (Fairclough et al , 2000 b ).…”

Breathing life into fisheries stock assessments with citizen science

“…Other than market sampling of commercial catches, the above approaches are usually expensive, particularly when sampling is required over several years and across a large geographical area. Ways to reduce field costs have included “self-sampling”, where a small number of commercial and/or recreational fishers are recruited to donate samples from their catch, usually with instructions on how to select samples, or by requesting recreational fishers to voluntarily donate samples from their catch to supplement active boat-ramp sampling2728293031.…”