Habitat patches that cross marine reserve boundaries: consequences for the lobster Jasus edwardsii.

Abstract

The spatial configuration of marine reserves should reflect management objectives. If reserves are intended to conserve ‘natural’ biological communities, then reserve boundaries should follow barriers to species movement, but if cross-boundary movement of harvestable individuals associated with certain habitat is desired for fisheries purposes, then boundaries should intersect that habitat. We relate movement patterns of the reef-associated spiny lobster Jasus edwardsii (Palinuridae) to the relative positions of habitat and reserve boundaries in a 24.5 km2 marine reserve on the temperate northeast coast of New Zealand by tagging >5000 individuals and recapturing a subset over 3 yr using pots. Lobster movement patterns were sex- and size-dependent, but nearly all recaptured individuals were found on the same rocky reef on which they were tagged, indicating that lobsters were reluctant to cross the muddy sediments between reefs. Lobsters became increasingly likely to migrate from the reserve into the heavily fished adjacent coast as the proportion of their reef that was unprotected increased. Corresponding changes in average catch per unit effort (CPUE) and size of all lobsters (tagged and untagged) occurred within the protected parts of the reefs, with lobster densities on a fully protected reef being 8-fold higher than densities on the protected part of a reef that was 91% unprotected.