Transplant monitoring for the New Jersey Delaware Bay oyster fisher.

摘要

New Jersey manages a quota-based fishery on its Delaware Bay oyster beds. A transplant program conducted each year to augment the quota moves a small proportion of oysters from upbay beds to downbay beds where the oysters quickly improve in market quality. High mortality rates downbay warrant minimizing the number of small oysters moved downbay and retaining recruitment potential warrants limiting the quantity of cultch moved downbay. Consequently, automatic cullers are used and each transplant is monitored. An observer study was conducted during the 2011 transplant to evaluate the method of transplant monitoring. Samples taken throughout the day were compared with samples taken at the end of the day to determine if end-of-day sampling was sufficient to characterize the entire deckload. No significant difference was found between samples taken periodically during the day and end-of-day samples in 7 of 9 observed deckloads. No significant differences were found between 3 end-of-day samples taken to characterize the deckload and a larger sampling intensity of 12; thus, the current sampling intensity of 3 end-of-day samples to describe the deckload is sufficient. Because of varying gear configurations and economic incentives to load the deck quickly, we also compared cultch fractions and oyster size frequencies among boats. Representative distributions from different boats, days, and beds in the observer data set suggest that boats differing by 6-7% in cultch fraction should be identified routinely as significantly different from other boats. Significant differences were observed in oyster size frequency among boat deckloads more often than in cultch fraction. Further study is needed to determine the extent to which gear configuration affects deckload composition.