Larval dispersal and fishing pressure influence recruitment in a coral reef fishery

Understanding larval connectivity patterns in exploited fishes is a fundamental prerequisite for developing effective management strategies and assessing the vulnerability of a fishery to recruitment overfishing and localised extinction. To date, however, researchers have not considered how regional variations in fishing pressure also influence recruitment. We used genetic parentage analyses and modelling to infer the dispersal patterns of bumphead parrotfish Bolbometopon muricatum larvae in the Kia fishing grounds, Isabel Province, Solomon Islands. We then extrapolated our Kia dispersal model to a regional scale by mapping the available nursery and adult habitat for B. muricatum in six regions in the western Solomon Islands, and estimated the relative abundance of adult B. muricatum populations in each of these regions based on available adult habitat and historical and current fishing pressure. Parentage analysis identified 67 juveniles that were the offspring of parents sampled in the Kia fishing grounds. A fitted larval dispersal kernel predicted that 50% of larvae settled within 30 km of their parents, and 95% settled within 85 km of their parents. After accounting for unsampled adults, our model predicted that 34% of recruitment to the Kia fishery was spawned locally. Extrapolating the spatial resolution of the model revealed that a high proportion of the larvae recruiting into the Kia fishing grounds came from nearby regions that had abundant adult populations. Other islands in the archipelago provided few recruits to the Kia fishing grounds, reflecting the greater distances to these islands and lower adult abundances in some regions. Synthesis and applications. This study shows how recruitment into a coral reef fishery is influenced by larval dispersal patterns and regional variations in historical fishing pressure. The scales of larval connectivity observed for bumphead parrotfish indicate that recruitment overfishing is unlikely if there are lightly exploited reefs up to 85 km away from a heavily fished region, and that small (<1 km2) marine-protected areas (MPAs) are insufficient to protect this species. We recommend greater efforts to understand the interactions between larval dispersal and gradients of fishing pressure, as this will enable the development of tailored fisheries management strategies

National assessment and planning for improved fish handling in Solomon Islands

The report summarizes the discussions and interviews with provincial fisheries officers (PFOs) at the annual PFO conference in Honiara, November 23, 2022.The report also identifies the next steps needed to build a program on fish handling based on input from participants at the Fish Innovation project reflection workshop in Nusatupe, May 16–19, 2023

Solomon Islands largest hawksbill turtle rookery shows signs of recovery after 150 years of excessive exploitation

The largest rookery for hawksbill turtles in the oceanic South Pacific is the Arnavon Islands, which are located in the Manning Strait between Isabel and Choiseul Province, Solomon Islands. The history of this rookery is one of overexploitation, conflict and violence. Throughout the 1800s Roviana headhunters from New Georgia repeatedly raided the Manning Strait to collect hawksbill shell which they traded with European whalers. By the 1970s the Arnavons hawksbill population was in severe decline and the national government intervened, declaring the Arnavons a sanctuary in 1976. But this government led initiative was short lived, with traditional owners burning down the government infrastructure and resuming intensive harvesting in 1982. In 1991 routine beach monitoring and turtle tagging commenced at the Arnavons along with extensive community consultations regarding the islands' future, and in 1995 the Arnavon Community Marine Conservation Area (ACMCA) was established. Around the same time national legislation banning the sale of all turtle products was passed. This paper represents the first analysis of data from 4536 beach surveys and 845 individual turtle tagging histories obtained from the Arnavons between 1991-2012. Our results and the results of others, reveal that many of the hawksbill turtles that nest at the ACMCA forage in distant Australian waters, and that nesting on the Arnavons occurs throughout the year with peak nesting activity coinciding with the austral winter. Our results also provide the first known evidence of recovery for a western pacific hawksbill rookery, with the number of nests laid at the ACMCA and the remigration rates of turtles doubling since the establishment of the ACMCA in 1995. The Arnavons case study provides an example of how changes in policy, inclusive community-based management and long term commitment can turn the tide for one of the most charismatic and endangered species on our planet

Parameter estimates from a linear model estimating the effect of time and beach on the mean number of nests sighted per night.

<p>The model includes interactions between beach and time, which are shown with the symbol ":". In parameterizing the model, the reference beach used was Big Maleivona.</p

Average number of nests sighted per night at Big Maleivona, Kerehikapa, Sikopo and Small Maleivona during the peak nesting period between 1991 and 2012.

<p>Grey bars show 95% confidence intervals around the regression line.</p

The four main islands that make up the Arnavons and their nesting beaches.

<p>The location of the Arnavons group is shown in the insert.</p

The seasonality of nesting hawksbill turtles in Arnavons.

<p>The grey vertical bars show the May-August period.</p

Trends in the average number of hawksbill nests laid per night in the Arnavons group during the peak season (May-August) between 1991–2012.

<p>Grey bars show 95% confidence intervals around the regression line.</p

Mean remigration period for cohorts of turtles in the years between 1991 and 2007.

<p>Blue line indicates predicted values for a poisson regression of migration period against years since 1991. Grey area indicates 95% confidence intervals around the regression line. The slop of the regression line indicates a reduction in the remigration interval by 0.5/yr.</p