Login | Create Account (DAF staff only)

Natural mortality of Trachurus novaezelandiae and their size selection by purse seines off south-eastern Australia

Broadhurst, M. and Kienzle, M. and Stewart, J. (2017) Natural mortality of Trachurus novaezelandiae and their size selection by purse seines off south-eastern Australia. ArXiv e-prints .

Full text not currently attached. Access may be available via the Publisher's website or OpenAccess link.

Article Link(s): https://arxiv.org/ftp/arxiv/papers/1705/1705.10001...

Abstract

The natural mortality (M) and purse-seine catchability and selectivity were estimated for Trachurus novaezelandiae, Richardson, 1843 (yellowtail scad)-a small inshore pelagic species harvested off south-eastern Australia. Hazard functions were applied to two decades of data describing catches (mostly stable at a mean +- SE of 315 +- 14 t p.a.) and effort (declining from a maximum of 2289 to 642 boat days between 1999/00 and 2015/16) and inter-dispersed (over nine years) annual estimates of size-at-age (0+ to 18 years) to enable survival analysis. The data were best described by a model with eight parameters, including catchability (estimated at < 0.1 x 10-7 boat day-1), M (0.22 year-1) and variable age-specific selection up to 6 years with a 50% retention among 5-year olds (larger than the estimated age at maturation). The low catchability implied minimal fishing mortality by the purse-seine fleet. Ongoing monitoring and applied gear-based studies are required to validate purse-seine catchability and selectivity, but the data nevertheless imply T. novaezelandiae could incur substantial additional fishing effort and, in doing, so alleviate pressure on other regional small pelagics.

Item Type:Article
Business groups:Animal Science
Keywords:Quantitative Biology - Populations and Evolution
Subjects:Aquaculture and Fisheries > Fisheries > Fishery research
Deposited On:01 Aug 2017 03:23
Last Modified:01 Aug 2017 03:23

Repository Staff Only: item control page