Differences in the relative abundance of abalone (Haliotis iris) in relation to the perceived status of two regional fisheries in New Zealand

Abstract

Population survey results and commercial catch data were obtained for two fisheries (PAU 5 & PAU 7) for the New Zealand abalone Haliotis iris. PAU 5 had greater catch rates and greater relative abundance of harvestable abalone (≥ 125 mm shell length) than areas of PAU 7, but PAU 5 is perceived by participants to be vulnerable whereas PAU 7 is perceived as sustainable. Contrasts in the relative abundance of juveniles (abalone in cryptic habitat < 100 mm shell length) and pre-recruits (≥ 100, < 125 mm) appear to correlate with the perception of participants on the sustainability of the two fisheries. For areas within individual fisheries, population surveys in 1993 and again in 1995/96 revealed no differences in the relative abundance of harvestable individuals. However, increases in the frequency of juveniles, pre-recruits, and large patches (≥ 5 individuals) were recorded for two of the three areas surveyed in PAU 7. No differences in any of these indices were found for PAU 5. These results suggest that perceptions of the sustainability of the New Zealand abalone fisheries relate to the relative levels of pre-recruits, particularly those individuals in large aggregations, rather than the abundance of harvestable individuals.

Keywords:

• Haliotis iris
• sustainability
• diver behaviour
• abundance
• aggregations