Reef Fisheries Research Articles

Trait groups as management entities in a complex, multispecies reef fishery.

Localized stressors compound the ongoing climate-driven decline of coral reefs, requiring natural resource managers to work with rapidly shifting paradigms. Trait-based adaptive management (TBAM) is a new framework to help address changing conditions by choosing and implementing management actions specific to species groups that share key traits, vulnerabilities, and management responses. In TBAM maintenance of functioning ecosystems is balanced with provisioning for human subsistence and livelihoods. We first identified trait-based groups of food fish in a Pacific coral reef with hierarchical clustering. Positing that trait-based groups performing comparable functions respond similarly to both stressors and management actions, we ascertained biophysical and socioeconomic drivers of trait-group biomass and evaluated their vulnerabilities with generalized additive models. Clustering identified 7 trait groups from 131 species. Groups responded to different drivers and displayed divergent vulnerabilities; human activities emerged as important predictors of community structuring. Biomass of small, solitary reef-associated species increased with distance from key fishing ports, and large, solitary piscivores exhibited a decline in biomass with distance from a port. Group biomass also varied in response to different habitat types, the presence or absence of reported dynamite fishing activity, and exposure to wave energy. The differential vulnerabilities of trait groups revealed how the community structure of food fishes is driven by different aspects of resource use and habitat. This inherent variability in the responses of trait-based groups presents opportunities to apply selective TBAM strategies for complex, multispecies fisheries. This approach can be widely adjusted to suit local contexts and priorities.

Climate-induced increases in micronutrient availability for coral reef fisheries

SummaryClimate change is transforming coral reefs, threatening supply of essential dietary micronutrients from small-scale fisheries to tropical coastal communities. Yet the nutritional value of reef fisheries and climate impacts on micronutrient availability remain unclear, hindering efforts to sustain food and nutrition security. Here, we measure nutrient content in coral reef fishes in Seychelles and show that reef fish are important sources of selenium and zinc and contain levels of calcium, iron, and omega-3 fatty acids comparable with other animal-source foods. Using experimental fishing, we demonstrate that iron and zinc are enriched in fishes caught on regime-shifted macroalgal habitats, whereas selenium and omega-3 varied among species. We find substantial increases in nutrients available to fisheries over two decades following coral bleaching, particularly for iron and zinc after macroalgal regime shifts. Our findings indicate that, if managed sustainably, coral reef fisheries could remain important micronutrient sources along tropical coastlines despite escalating climate impacts.

Hidden benefits and risks of partial protection for coral reef fisheries

Partially protected areas are now the dominant global form of spatial management aimed at preserving ecosystem integrity and managing human use. However, most evaluations of their efficacy use only a narrow set of conservation indicators that reflect a fraction of ways in which protection can succeed or fail. In this paper, we examine three case studies of partially protected coral reef fishery systems to evaluate benefits and risks of their use as a management tool. We use data from community-based management arrangements in three Pacific Island countries to demonstrate three vignettes of how partial protection can boost fisheries production, enhance the ease with which fishers catch their prey, and alter the composition of fisheries yields. These changes in fisheries productivity, catchability, and vulnerability under partial protection carry substantial benefits for fishers. However, they also carry significant risks for ecosystems and fisheries livelihoods unless adaptively managed so as to confer the short to medium term benefits in resource performance without risking longer term sustainability.

Correction to: Gear selectivity of functional traits in coral reef fisheries in Brazil

Correction to: Gear selectivity of functional traits in coral reef fisheries in Brazil

An experimental evaluation of the effect of escape gaps on the quantity, diversity, and size of fish caught in traps in Montserrat.

Coral reef fisheries are vital to the livelihoods of millions of people worldwide but are challenging to manage due to the high diversity of fish species that are harvested and the multiple types of fishing gear that are used. Fish traps are a commonly used gear in reef fisheries in the Caribbean and other regions, but they have poor selectivity and frequently capture juvenile fish, impacting the sustainability of the fishery. One option for managing trap fisheries is the addition of escape gaps, which allow small fish to escape. We compared catches of traps with and without two 2.5 cm (1 inch) escape gaps on the Caribbean island of Montserrat. No significant differences were found in the mean fish length, total fish biomass, number of fish, fish species richness, and Shannon diversity index between hauls of the two trap designs, though traps with escape gaps did catch larger proportions of wider-bodied fish and smaller proportions of narrow-bodied fish. Furthermore, traps with gaps caught a smaller proportion of small-sized fish and fewer immature fish (though differences were not statistically significant). Linear mixed effect models predict that soak time (the length of time between trap hauls) increases the mean catch length, total catch biomass and total number of species in the catch. The relatively modest evidence for the effect of the gaps on catch may be explained by the long soak times used, which could have allowed most smaller-sized fish to escape or be consumed by larger individuals before hauling in both traps with and without escape gaps. Despite the small differences detected in this study, escape gaps may still offer one of the best options for improving sustainability of catches from fish traps, but larger escape gaps should be tested with varying soak times to determine optimum escape gap size.

Scraping and grazing herbivorous/detritivorous fish display opposite feeding behaviours under different protection regulations

ABSTRACT Herbivorous and detritivorous fish display complex feeding behaviour, and research into how feeding behaviour changes with environmental and social variables is lacking. Such knowledge is imperative to infer how herbivory/detritivory will differ, in light of shifting resources and communities and specifically whether reefs can recover from disturbance. Fish abundance, feeding rate, body size, diet and schooling feeding of three major functional groups (scrapers, grazers and browsers) were examined across reef types under different fishing regulations. Scrapers and grazers (parrotfishes and surgeonfishes) were more abundant and displayed the highest feeding rates on reef flats. Scrapers mainly resided inside the restricted zone, while more grazers were found in the general use zone, where macroalgal abundance was highest. Browsers (rabbitfishes) were seldom observed and patchily gathered on the reef flat and reef slope in both zones. Thus, fishing protection did not appear to benefit grazers and browsers, whereas more scrapers gathered on shallow reef flats in the protection zone. Scraper and grazer feeding rates increased from an individual to a pair and increased with body size, these factors led to variations in feeding behaviours across reef types and protection regulations. Protection appears to benefit scrapers and variations in feeding rates were largely related to school size. Lastly, grazer density was associated more with macroalgal coverage than protection status. The opposite feeding behaviours of scrapers and grazers indicates not only protection status, but fishing restrictions and size limit regulations are needed to maintain coral reef fisheries and functional diversity on coral reefs in Taiwan.

What's wrong with the coastal waters of Spelman Strait, Indonesia: Sustainable reef fisheries management is required

Reef fish in Spelman strait, Indonesia, is one of the fishery resources of considerable economic value. Unfortunately, there is still the use of unfriendly resources equipment (destructive fishing) that cause potential social problems. In this study, all components of the EAFM (Ecosystem Approach to Fisheries Management) composed of 6 domains, namely (1) fish stocks, (2) environment and ecosystem, (3) fishing techniques, (4) culture, (5) social, and (6) institutional are analyzed combining with MDS (Multidimensional Scaling). The main aim of this research is to find out the root solution for managing coral reefs in the coastal waters of Spelman Strait. The sustainability status review in the fishery resource domain, the environment and ecosystem domain, the fishery technique domain, the social domain, and the economic domain were respectively were 87.69, 88.17, 51.22, 51.61, and 72.67 which were in the category sustainable. Meanwhile, the sustainability status review in the institutional domain was 42.15, which was in the category of less sustainable. Institutions are the primary base for reef fishery protection in the Spelman Strait.

Gear selectivity of functional traits in coral reef fisheries in Brazil

Gear selectivity of functional traits in coral reef fisheries in Brazil

Mortality and exploitation rate of some reef fish in Ternate Island Waters

Fish population dynamics are determined by the balance between population increase resulted from growth and addition of new individuals (recruitment), and population decrease due to fishing mortality and natural mortality. It is important to understand fish resources condition, including their change pattern caused by pressures on coral reef fisheries resource in coastal area of Ternate Island. This research aimed to analyze mortality and exploitation rate of several reef fishes that caught at coastal area of Ternate Island. Stock assessment method was used to determine the mortality and exploitation rate of some reef fishes. Study results showed that the fishing mortality of the sample species was lower than their natural mortality, while the exploitation rate results also showed the same condition those found in mortality rate, where the fish with high growth coefficient tended to have high mortality rates.

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

Abstract 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.

Global decline in capacity of coral reefs to provide ecosystem services

Global decline in capacity of coral reefs to provide ecosystem services

Gear restrictions create conservation and fisheries trade‐offs for management

AbstractGear‐based management for coral reef fisheries is often overlooked in the scientific literature. Empirical studies have demonstrated the conservation benefits of gear‐restricted areas (i.e. prohibiting fishing gears), which can support greater biomass than unrestricted areas and protect species that play key functional roles. However, population dynamics of functional feeding groups of reef fishes under specific gear‐restriction regimes remains uncertain. Here, we constructed a multi‐species, length‐based fisheries model to observe relative biomass and catch of reef fishes under various gear‐restriction management scenarios. We used fishery‐dependent and fishery‐independent data to determine the catchability of functional groups and selectivity of size classes for hook‐and‐line, net and spear fishing, which are widely used gear types on coral reefs globally. Our model revealed trade‐offs involved with gear‐restriction management such that no single management strategy was able to maximize biomass or catch of all functional groups simultaneously. Also, we found that spear fishing (i.e. prohibiting hook‐and‐line and net fishing) maintained the highest total biomass summed across functional groups, whilst hook‐and‐line fishing (i.e. prohibiting net and spear fishing) and a ban on spears maintained the lowest biomass. However, hook‐and‐line fishing generated the highest catch‐per‐unit‐effort. Our model results were primarily driven by differential growth rates, maximum per capita production of recruits, and catchability of functional groups targeted by each fishing gear. We demonstrate that gear restrictions can be a critical management tool for maintaining biomass and catch of certain functional groups but will likely require additional management to protect all key functional feeding groups of coral reef fishes.

Reef Conservation off the Hook: Can Market Interventions Make Coral Reef Fisheries More Sustainable?

The overexploitation of coral reef fisheries threatens the persistence of reef ecosystems and the livelihoods and food security of millions of people. Market-based initiatives to increase fisheries sustainability have been widely implemented in industrialized commodity fisheries, but the suitability of these initiatives for coral reef fisheries has not been systematically investigated. Here, we present a typology of market-based interventions and coral reef fisheries sectors and identity promising approaches for each fishery archetype. For high value, export-oriented reef fisheries that are highly unsustainable (live reef food fish and dried sea cucumbers), traditional regulatory efforts including trade restrictions will be most effective. For high-value, export-oriented fisheries for highly fecund invertebrates (lobsters and mollusks), certification and ratings efforts, fishery improvement projects, and sustainable purchasing commitments can improve fishing practices and increase fisher market access and revenue. For lower-value fisheries targeting species for domestic or regional consumption, sustainable purchasing commitments among local buyers, consumer awareness campaigns, and local certification and ratings schemes hold promise for shifting attitudes toward sustainability and increasing food security for local communities. Finally, fisher empowerment efforts including direct access to local markets and market information, training on improved post-harvest methods, and formation of fisher associations hold promise for increasing fisher incomes, reducing wasteful catch, increasing food security, and de-incentivizing unsustainable practices. Despite the potential of market-based interventions, specific approaches must be carefully tailored to the ecological and social reality of these systems, including the inherent unsustainability of commercial coral reef fisheries, the limited capacity for fisheries governance, the limited financial support of market-based initiatives, and the threatened status of coral reef ecosystems globally.

Initiating Napoleon wrasse (Cheilinus undulatus Ruppell, 1835) as watching species object in Banda Islands marine ecotourism

Banda islands is a small island geographically located in the Banda Sea, Maluku Province, the eastern part of Indonesia. Livelihoods consist of agriculture, plantation, animal husbandry, and fishery activities. The number of fisher households is 1576 with 3278 fishers. From 2239 units of fishing gear, 75% of them are intended to utilize tuna and tuna-like fishes as their daily livelihood. Coral reef fisheries relatively limited numbers, so that reef fish exploitation is somewhat low pressure. Therefore, the area has a high fish diversity index and likely to be a diving tourism object. An area of 2500 Ha of Marine Protected Area (MPA) Banda Sea was established in 1977. Napoleon wrasse, Cheilinus undulatus Ruppell, 1835, one of the biggest coral fish had been classified by The IUCN Red List as endangered species is somewhat easy to find in this area. From our observation, the species are commonly found in shallow coral reef waters. The estimated density was 7.13 individuals per hectare with a size between 10 - 90 cm total length. The descriptive analysis was applied by utilizing several observations in 2018 through diving operator surveys, interviews, and digital literature reviews. This study aimed to estimate the potential benefit of initiating watching tourism as the prospect of sustainable socio-economic services. Therefore, it expects to be a new economic alternative livelihood for Banda small island coastal community. With the combination of existing MPA and Napoleon wrasse presence, this study would strongly contribute to the MPA economy and ecology values and its surroundingswaters under SDG’s 14 to maximize the conservation area benefits.

Understanding the Dynamics of Kelp Forest Recovery from Fishing

Photo 1. Kelp forests provide numerous ecosystem services, including support for economically important fishery species. In southern California, USA, including the Channel Islands shown in the background above, kelp forests provide habitat for the spiny lobster Panulirus interruptus, which is the focus of a trap-based fishery. Photo credit: Robert Dunn. Photo 2. Herbivores can overgraze macroalgae on rocky reefs, leading to a transition from kelp forest to urchin barren. Here, a research diver surveys densities of purple and red sea urchins (Strongylocentrotus purpuratus and Mesocentrotus franciscanus, respectively) in a barren habitat at Santa Barbara Island, California, USA. In some cases, urchin barrens can form due to overharvest of kelp forest predators. Red urchins are themselves the focus of a targeted fishery, but urchins from barrens are typically not harvested due to their low gonad mass. Photo credit: Robert Dunn. Photo 3. When rocky reef fisheries are effectively managed, kelp forests can, in many instances, recover to their macroalgal-dominated state. Photo credit: Robert Dunn. These photographs illustrate the article “Transient dynamics during kelp forest recovery from fishing across multiple trophic levels” by Robert P. Dunn, Jameal F. Samhouri, and Marissa L. Baskett published in Ecological Applications. https://doi.org/10.1002/eap.2367.

Spawning aggregation sites of the cubera snapper, Lutjanus cyanopterus, on the continental shelf of Bahia state, Northeastern Brazil

The cubera snapper (caranha), Lutjanus cyanopterus, is an important resource for reef fisheries in Northeastern Brazil, currently classified as Vulnerable (VU) on the Red List of Threatened Species. This species forms large transient reproductive aggregations, concentrating their reproductive efforts in a short period of the year and in specific spawning sites, which have already been well documented in the Caribbean. These aggregations are predictable in time and space, making them considerably vulnerable to overfishing and other sources of anthropic impacts. These tend to reduce the population’s renewal capacity and genetic diversity, thus contributing to the decline of fish stocks and to the process of local extinctions. Between 2009 and 2010 we identified two L. cyanopterus aggregation sites, commonly known as “Caranheiros”, in two sub-areas located at the continental shelf-break zone of Bahia state, Northeastern Brazil, in the East Brazil Shelf Large Marine Ecosystem (LME16), between latitudes 12 °S and 15 °S. The present study aims to (1) describe patterns of spatial and temporal distribution, and the biological characteristics of L. cyanopterus’ catches from line fisheries targeting the specific aggregations in the two Caranheiros sites; and (2) validate the reproductive character of these aggregations through macroscopic evaluation of sexual maturity phases of the fishes caught. We analyzed fisheries and biological sampling data from the catches of artisanal fleets monitored in the two sub-areas between 2005 and 2014. The identified aggregations occur annually from December to May, with capture peaks concentrated in waning to waxing moon phases, in January, February and March. The predominance of mature, pre-spawning and spent (recent spawning) individuals, males and females, in these aggregations revealed the reproductive activity in both sites. Identifying and validating these spawning sites may contribute to the development of recovery and conservation plans for this threatened species. The continuous monitoring of fisheries on aggregations is a priority, aiming to trigger management responses and adaptative fisheries management. Considering these sites are highly vulnerable and have high local socioeconomical importance, especially to traditional fishers, the exact location of the analyzed “Caranheiros” is not revealed in this publication. However, it has been made available to the government agencies responsible for fisheries control and surveillance, as well as for implementing management and conservation measures for the sustainable use of fisheries resources.

Views of management effectiveness in tropical reef fisheries

AbstractThe effectiveness and outcomes of management are expected to improve when people are informed, engaged and influential in governance and management procedures. The social‐ecological and demographic contexts should, however, influence an individual's perceptions and willingness to engage and access appreciable benefits from management. To evaluate how engagement, procedures and perceived outcomes varied with geographic and social‐ecological context, we asked 1582 heads‐of‐households in 38 fishing villages in four tropical countries to evaluate the benefits of their local fisheries management. Responses to 10 collective action, social performance and management procedure questions fell along three response axes, namely (a) the potential benefits of management, (b) resource status and the reliability of yields and (c) the respondents' ability to influence management decisions. Respondents were most positive about the organization of the existing management systems but more sceptical about their ability to influence decision‐making and subsequent yields and resource status. More frequent negative opinions increased with urbanization (distance to cities and population density), which could arise from challenges of group cohesion, local control and subsequent management efficacy. Consequently, we argue that some common rural, decentralized, or collective fisheries management systems are inappropriate for engaging participation in urban contexts. Across all locations, there is a need to increase participation with management decisions and actions, and to transparently evaluate and respond to resource and yield outcomes. Crafting recommendations appropriate for urban contexts will be increasingly relevant as urbanization and commercialized fisheries expand in tropical countries.

Effects of habitat, fishing, and fisheries management on reef fish populations in Palau

Palau has a rich tradition of fisheries management and stewardship of its waters, and as in many island nations, small-scale coral reef fisheries are a vital part of the local culture, economy, and food security. However, reef fisheries in Palau are data-poor and there is increasing concern that reef fish stocks are declining. To evaluate the current and future status of these resources, information is needed on the abundance, biomass, and size structure of reef fish resource species. To this aim, the Palau International Coral Reef Center (PICRC) conducted a nation-wide study to investigate the status of commercially important reef fish stocks in 2017. Fishery-independent surveys were conducted by diver operated stereo-video (stereo-DOV) at 94 sites across the archipelago. Results showed that fish biomass varied from 0.13 to 293 g m−2. Habitat was the most significant predictor of fish biomass, with the highest biomass found at western fore-reef sites and the lowest at inner reef sites. Region also affected fish biomass, with significantly higher biomass found in the Northern Reefs compared to those around Babeldaob (the largest island in Palau). In channel habitats, marine protected area (MPA) proximity, fishing pressure from Koror (Palau’s main population center), and local fishing pressure significantly influenced fish biomass. In western fore-reef habitats, fish biomass was significantly affected by region, with differences observed between the Northern Reefs and Babeldaob, and between the Southern Reefs and Babeldaob. Fishing pressure from Koror had a significant effect on fish biomass in inner reef habitats, with a weak negative relationship observed. Using length frequencies from the stereo-DOV surveys we also estimated spawning potential ratio (SPR) for seven species and found the majority had SPR values between 20 % and 40 %. Overall, the low fish biomass and SPRs suggests that many of Palau’s principal fisheries species have been overexploited. This is the first study to evaluate the status of resource reef fish stocks across the main islands of Palau and provides a baseline to assess changes in fish populations over time.

Fishing and habitat condition differentially affect size spectra slopes of coral reef fishes.

Marine food webs are structured through a combination of top-down and bottom-up processes. In coral reef ecosystems, fish size is related to life-history characteristics and size-based indicators can represent the distribution and flow of energy through the food web. Thus, size spectra can be a useful tool for investigating the impacts of both fishing and habitat condition on the health and productivity of coral reef fisheries. In addition, coral reef fisheries are often data-limited and size spectra analysis can be a relatively cost-effective and simple method for assessing fish populations. Abundance size spectra are widely used and quantify the relationship between organism size and relative abundance. Previous studies that have investigated the impacts of fishing and habitat condition together on the size distribution of coral reef fishes, however, have aggregated all fishes regardless of taxonomic identity. This leads to a poor understanding of how fishes with different feeding strategies, body size-abundance relationships, or catchability might be influenced by top-down and bottom-up drivers. To address this gap, we quantified size spectra slopes of carnivorous and herbivorous coral reef fishes across three regions of Indonesia representing a gradient in fishing pressure and habitat conditions. We show that fishing pressure was the dominant driver of size spectra slopes such that they became steeper as fishing pressure increased, which was due to the removal of large-bodied fishes. When considering fish functional groups separately, however, carnivore size spectra slopes were more heavily impacted by fishing than herbivores. Also, structural complexity, which can mediate predator-prey interactions and provisioning of resources, was a relatively important driver of herbivore size spectra slopes such that slopes were shallower in more complex habitats. Our results show that size spectra slopes can be used as indicators of fishing pressure on coral reef fishes, but aggregating fish regardless of trophic identity or functional role overlooks differential impacts of fishing pressure and habitat condition on carnivore and herbivore size distributions.

Cumulative impact assessments highlight the benefits of integrating land-based management with marine spatial planning

Cumulative impact assessments can inform ecosystem-based management by mapping human pressures and assessing their intensity on ecosystem components. However, its use to inform local management is scarce, largely due to the need for fine-grained spatial data representing ecosystem threats that can assess impacts at a local scale. Here, we applied the cumulative impact assessment framework to Moorea's coral reef, French Polynesia to inform the ongoing revision of the island-wide marine spatial management plan. We combined high spatial resolution data on 11 local anthropogenic pressures and four ecological components with expert vulnerability assessments. Results revealed that the entire reef is impacted by at least four pressures: coral reef fisheries, agriculture, land use change and urbanization. These activities together contribute to 87% of the overall cumulative impact. Most importantly, land-based activities contribute to more than half (52%) of the overall impact. Other high-impact activities, such as reef-based tourism, remain very localized and contribute little to the overall human impact. These findings show that by focusing solely on reef-based activities, the current management plan misses critical sources of impact. Not considering land-based activities in the management may lead to decisions that could fail to significantly lower cumulative human impact on the reef. This study demonstrates how operationalizing the cumulative human impact framework at a local scale can help managers identify key leverage points likely to yield improved ecological outcomes.