Effects of marine reserve protection on spiny lobster (Jasus edwardsii) abundance and size at Tonga Island Marine Reserve, New Zealand

Abstract

ABSTRACT1. Diving surveys were undertaken to investigate the effects of marine reserve protection on spiny lobster (Jasus edwardsii) populations at Tonga Island Marine Reserve, northern South Island, New Zealand over a 2 year period from December 1998 to December 2000.2. Spiny lobsters were 2.8 times more abundant overall, and mean size was 19 mm carapace length larger in shallow transects and 28 mm carapace length larger in deep transects, in the marine reserve than at adjacent fished sites. That pattern was evident despite very high variability within sites, and among sites within reserve and fished areas.3. Large reproductive males were 10 times more abundant within the reserve compared to adjacent fished areas, suggesting that more eggs would be fertilized in the reserve than on the adjacent fished coast.4. Estimates of size-specific fecundity, combined with abundances of females, suggested that almost nine times more eggs would be produced in the reserve than in fished areas.5. Diving and commercial trapping investigations found weak trends in spiny lobster abundance consistent with gradients at reserve borders. Tagging investigations near those borders led to only one resighting of a tagged spiny lobster.6. We estimate that the mean abundance of spiny lobster in the reserve has increased by 22%, 5 years after its establishment, indicating an annual population increase of 4.4%. Over the same period, abundance of spiny lobster outside the reserve has declined by 2.9% per annum.7. Based on known spiny lobster movements, we suggest that marine reserves of more than 10 km length should be given priority over smaller reserves. Smaller reserves will, however, protect part of the population for at least a portion of their lifespan.8. Previous studies of movement of J. edwardsii suggest that spillover from the reserve should occur, and as population density increases we predict that more spiny lobsters will move out from the reserve.

Effects of marine reserve protection on the mud crab Scylla serrata in a sex-biased fishery in subtropical Australia

“…Previous studies of S. serrata in Moreton Bay have found higher catches of crabs in summer compared to winter (Williams & Hill 1982). Our results are consistent with similar studies in which increases in catch rates (CPUE) of invertebrates have been detected in reserves worldwide (gastropod and sea urchin, Castilla 1996; gastropod, sea urchin and limpet, Castilla & Fernandez 1998; abalone and lobster, Edgar & Barrett 1999;lobster, Kelly et al 2000, Davidson et al 2002. Interestingly, the catch rates of S. serrata were almost identical between both marine reserves despite the Tripcony Bight reserve being 3 times larger in size than the Willes Island reserve.…”

“…The skewed size distribution of male crabs in both marine reserves in this study further reflects the impact the mud crab fishery has in Moreton Bay. Increases in the average size of crustaceans have also been detected in marine reserves for spiny lobster Jasus edwardsii in New Zealand (Kelly et al 2000, Davidson et al 2002 and American lobster Homarus americanus in Newfoundland (Rowe 2002). In contrast, the average size of female S. serrata in our study did not differ greatly between the reserve and non-reserve sites which is probably due to the total protection offered to female crabs at all study sites.…”

“…We are not aware of any studies that assess the impacts of a sex-biased (invertebrate) fishery together with the effects of marine reserve protection; however, a number of studies looking at sex ratios of the partially protected (i.e. protection of ovigerous females) spiny lobster Jasus edwardsii in New Zealand have revealed differences in sex ratios of J. edwardsii between marine reserves and adjacent fished sites (MacDiarmid & Breen 1992, Davidson et al 2002, Kelly et al 2002. Due to the intense fishing pressure, limited movement and relatively well-established populations within Moreton Bay, S. serrata was chosen as the species most likely to show dramatic responses to reserve protection.…”

Spillover of spiny lobsters Palinurus elephas from a marine reserve to an adjoining fishery

“…These studies have generally shown higher values closer to reserve centres for target species of low to moderate mobility. Similar results have been obtained in the few lobster studies available (Kelly et al 2002, Davidson et al 2002. The most convincing evidence of benefits to nearby fisheries from this type of study is the build-up of reef fish biomass (for over 2 decades) adjacent to a marine reserve in the Philippines (Russ et al 2004).…”

Relationships between mobile macroinvertebrates and reef structure in a temperate marine reserve

“…Rock lobsters and large carnivorous fish have been shown to increase in size and abundance in temperate marine protected areas (MPAs) in Tasmania (Edgar & Barrett 1997, Barrett et al 2009) and New Zealand (Babcock et al 1999, Davidson et al 2002, Shears & Babcock 2002. Structural features such as crevices, holes or overhangs can offer physical refuges to reduce the predatory efficiency of these predators (Drolet et al 2004a), dampening their impact on prey populations.…”