Developing indices of abundance for inshore pelagic finfish from opportunistic aerial sightings data
NIWA, PO Box 11115, Hamilton, New Zealand
Email: p.taylor@niwa.co.nz
Inshore schooling species like blue mackerel (Scomber australasicus), jack mackerel (Trachurus spp.), kahawai (Arripis trutta), and trevally (Pseudocaranx dentex) are important members of the pelagic community. A large proportion of their landings are taken in the purse-seine fishery where catch rate is a particularly poor estimator of abundance. Fish-spotting pilots are an integral part of the purse-seine operation. They identify schools of the required size and species composition and assist with setting the gear. They also record details of schools sighted, which are the basis of a database that can provide spatial and temporal information as well as the amount of these species in surface schools back to 1976. I will discuss characteristics of the opportunistic data collection, how these translate into difficulties for data analysis, and the various approaches taken to derive indices of abundance using these data.
Room 3 Friday 10.50 am
