Marine Reserves Research Articles

Catch per Unit Effort of Decapod Species, C. pagurus and H. gammarus, from a Voluntary Marine Reserve

C. pagurus and H. gammarus are deemed to be declining in abundance in the Berwickshire Marine Reserve from personal communications with local inshore fishers. Fisheries data in the form of catch per unit effort (CPUE) were collected for these two commercially important decapods. Other explanatory variables from fishing activity such as the creel and bait type used, the soak time of the fishing gear, and deployment depth were recorded to provide as much detail as possible to describe the effort applied to catch these decapod species. In this study, CPUE was higher for H. gammarus and C. pagurus outside the Berwickshire Marine Reserve. General additive models (GAMs) were used to describe the effects of the explanatory variables and showed that soak time (days) and depth (m) significantly affected CPUE for C. pagurus, not H. gammarus. Sea temperature (°C) showed a negative correlation with the CPUE of both H. gammarus and C. pagurus; however, a positive correlation was found with the number of C. pagurus caught. The data collected in this study provide a foundation in understanding the current abundance of C. pagurus and H. gammarus in a voluntary marine reserve on the east coast of Scotland, which can be used to inform future changes in fisheries management in Berwickshire.

The Sponges of the Carmel Pinnacles Marine Protected Area.

California's network of marine protected areas was created to protect the diversity and abundance of native marine life, but the status of some taxa is very poorly known. Here we describe the sponges (phylum Porifera) from the Carmel Pinnacles State Marine Reserve, as assessed by a SCUBA-based survey in shallow waters. Of the 29 sponge species documented, 12 (41%) of them were previously unknown. Using a combination of underwater photography, DNA sequencing, and morphological taxonomy, we greatly improve our understanding of the status and distribution of previously described species and formally describe the new species as Hymedesmia promina sp. nov., Phorbas nebulosus sp. nov., Clathria unoriginalis sp. nov., Clathria rumsena sp. nov., Megaciella sanctuarium sp. nov., Mycale lobos sp. nov., Xestospongia ursa sp. nov., Haliclona melissae sp. nov., Halichondria loma sp. nov., Hymeniacidon fusiformis sp. nov., Scopalina carmela sp. nov., and Obruta collector gen. nov., sp. nov. An additional species, Lissodendoryx topsenti (de Laubenfels 1930), is moved to Hemimycale, and H. polyboletus comb. nov., nom. nov. is created due to preoccupation by H. topsenti (Burton, 1929). Several of the new species appear to be rare and/or have very restricted distributions, as they were not found at comparative survey sites outside of Carmel Bay. These results illustrate the potential of qualitative presence/absence systematic surveys of understudied taxa to discover and document substantial novel diversity.

Biomass of key grazing fishes is an important determinant of coral growth and fouling control in coral nurseries

Restoration is an emerging tool for coral reef conservation, yet despite small‐scale successes there are concerns about high costs and ecological setbacks. Integration between reef ecology and restoration could help address such concerns. A prime example is the use of grazing by herbivores to reduce coral nursery cleaning costs. However, the relation between herbivore communities and cleaning benefits remains unquantified. This study aimed to measure links between herbivorous fish communities, grazing intensity and coral nursery performance. Six reefs were selected in southern Kenya, equally divided across three levels of fisheries management (fished < reserve < no‐take). Fish surveys determined herbivorous fish biomass and composition, and remote underwater videos recorded grazing intensity on coral nurseries. Accumulated fouling and coral growth were measured at the end of the 4‐month study. Grazing intensity was sixfold lower and fouling density fourfold higher in the fished areas compared to protected zones. Higher fouling strongly correlated with lower coral growth: exponential growth constants in fished areas were respectively twice and three times as low compared to marine reserves and no‐take zones. Across study sites grazing was dominated by bristletooth tangs (Ctenochaetus spp.), except where these were outcompeted by territorial damselfish. Thus, better coral nursery performance in protected areas can be partially linked to higher grazing intensity, which in turn is determined by both fish biomass and local species composition. We recommend protecting herbivorous fish species and placing coral nurseries in areas with high biomass of key grazers to improve coral nursery performance and reduce maintenance costs.

A marine protected area network does not confer community structure resilience to a marine heatwave across coastal ecosystems.

Marine protected areas (MPAs) have gained attention as a conservation tool for enhancing ecosystem resilience to climate change. However, empirical evidence explicitly linking MPAs to enhanced ecological resilience is limited and mixed. To better understand whether MPAs can buffer climate impacts, we tested the resistance and recovery of marine communities to the 2014-2016 Northeast Pacific heatwave in the largest scientifically designed MPA network in the world off the coast of California, United States. The network consists of 124 MPAs (48 no-take state marine reserves, and 76 partial-take or special regulation conservation areas) implemented at different times, with full implementation completed in 2012. We compared fish, benthic invertebrate, and macroalgal community structure inside and outside of 13 no-take MPAs across rocky intertidal, kelp forest, shallow reef, and deep reef nearshore habitats in California's Central Coast region from 2007 to 2020. We also explored whether MPA features, including age, size, depth, proportion rock, historic fishing pressure, habitat diversity and richness, connectivity, and fish biomass response ratios (proxy for ecological performance), conferred climate resilience for kelp forest and rocky intertidal habitats spanning 28 MPAs across the full network. Ecological communities dramatically shifted due to the marine heatwave across all four nearshore habitats, and MPAs did not facilitate habitat-wide resistance or recovery. Only in protected rocky intertidal habitats did community structure significantly resist marine heatwave impacts. Community shifts were associated with a pronounced decline in the relative proportion of cold water species and an increase in warm water species. MPA features did not explain resistance or recovery to the marine heatwave. Collectively, our findings suggest that MPAs have limited ability to mitigate the impacts of marine heatwaves on community structure. Given that mechanisms of resilience to climate perturbations are complex, there is a clear need to expand assessments of ecosystem-wide consequences resulting from acute climate-driven perturbations, and the potential role of regulatory protection in mitigating community structure changes.

Ecotourism impacts on reef fishes in a marine reserve during the COVID‐19 era

Marine reserves generally permit ecotourism within their boundaries as a source of income for local communities, but the impacts of ecotourism on wildlife are still poorly understood. The lockdown resulting from the COVID‐19 pandemic in 2020 provided a unique opportunity to evaluate wildlife diversity in the absence of human activity. In a marine reserve in Mexico, we monitored fish assemblages before, during, and immediately after the lockdown to examine ecotourism impacts on fish assemblages. Our results show that fish density rose 2.5‐fold during the lockdown, suggesting that ecotourism activities alter fish behavior. We suggest that the presence of divers and noise pollution generated by recreational vessels are important disturbance factors. In the absence of human activity, however, some fish may be more bold (hide less often) or may return to the reserve after having retreated to more tranquil (deepwater) areas. We hope that our findings spur efforts to improve the health of marine reserves through the establishment of effective management strategies to mitigate ecotourism impacts.

Inter-nesting, migration, and foraging behaviors of green turtles (Chelonia mydas) in the central-southern Red Sea

Sea turtles are migratory with nesting and foraging areas in distinct and often widely separated habitats. Telemetry has been a vital tool for tracking sea turtle migrations between these areas, but tagging efforts are often focused on only a few large rookeries in a given region. For instance, turtle tagging in the Red Sea has been focused in the north of the basin. We tagged five green turtles (Chelonia mydas) at a nesting site in the central-southern Red Sea and tracked them for 72–243 days. During the inter-nesting period, the turtles showed high site-fidelity, with a maximum home range of 161 km2. After the nesting season, the turtles migrated up to 1100 km to five distinct foraging locations in three countries (Saudi Arabia, Sudan, and Eritrea). Movements within foraging habitats were more wide-ranging compared to inter-nesting movements, with home ranges varying between 1.19 and 931 km2. The tracking data revealed that the creation of a relatively small marine reserve could protect the critical inter-nesting habitat in the Farasan Banks. The results also highlight the need for multinational collaboration to protect migratory corridors and foraging sites of this endangered species.

Building a Practical Multi-Sensor Platform for Monitoring Vessel Activity near Marine Protected Areas: Case Studies from Urban and Remote Locations

Monitoring vessel activity is an important part of managing marine protected areas (MPAs), but small-scale fishing and recreational vessels that do not participate in cooperative vessel traffic systems require additional monitoring strategies. Marine Monitor (M2) is a shore-based, multi-sensor platform that integrates commercially available hardware, primarily X-band marine radar and optical cameras, with custom software to autonomously track and report on vessel activity regardless of participation in other tracking systems. By utilizing established commercial hardware, the radar system is appropriate for supporting the management of coastal, small-scale MPAs. Data collected in the field are transferred to the cloud to provide a continuous record of activity and identify prohibited activities in real-time using behavior characteristics. To support the needs of MPA managers, both hardware and software improvements have been made over time, including ruggedizing equipment for the marine environment and powering systems in remote locations. Case studies are presented comparing data collection by both radar and the Automatic Identification System (AIS) in urban and remote locations. At the South La Jolla State Marine Reserve near San Diego, CA, USA, 93% of vessel activity (defined as the cumulative time vessels spent in the MPA) was identified exclusively by radar from November 2022 through January 2023. At the Caye Bokel Conservation Area, within the Turneffe Atoll Marine Reserve offshore of Belize, 98% was identified exclusively by radar from April through October 2022. Spatial and temporal patterns of radar-detected and AIS activity also differed at both sites. These case study site results together demonstrate the common and persistent presence of small-scale vessel activity near coastal MPAs that is not documented by cooperative systems. Therefore, an integrated radar system can be a useful tool for independent monitoring, supporting a comprehensive understanding of vessel activity in a variety of areas.

Modelling spatial variation in an exploited species across marine reserve boundaries

Abstract An increase in exploited species within marine reserves is often expected to benefit adjacent fished areas through the movement or ‘spill‐over’ of exploited species across reserve boundaries. However, harvest at and near reserve boundaries can also decrease abundances inside reserves, forming ‘edge‐effects’. Spatial analysis of gradients in abundance across reserve boundaries have been used to interpret the extents of edge‐effects and spill‐over. While the shape of these gradients will vary depending on species mobility and fishing intensity on reserve boundaries, they have largely been assumed to be gradual and quantified using continuous modelling strategies. This study shows that continuous modelling strategies can lead to overestimations of spill‐over and edge‐effects by underfitting the rapid transition in abundance that can occur from reserve to fished areas. The abundances of spiny lobster (Jasus edwardsii) across the boundaries of two north‐eastern New Zealand marine reserves were quantified using catch survey data collected over 2 years. Several modelling approaches were used, and the predictive performance of each approach was compared. Abrupt changes in lobster abundances were found across reserve boundaries and were best represented with models that incorporated a stepwise function across boundaries or where data from reserve and fished areas were modelled independently. Despite the mobile nature of this species, we found little evidence of edge‐effects and spill‐over within and adjacent to the surveyed marine reserves, which may reflect the low population status within these reserves. In contrast, standard continuous modelling approaches overestimated the extent of edge‐effects and spill‐over in both marine reserves. Policy implications. This study shows how accurate assessments of edge‐effects and spill‐over can be used to evaluate the effectiveness of existing marine reserves in protecting exploited species. These findings emphasise the importance comparing several different modelling strategies when evaluating edge‐effects and spill‐over to ensure appropriate model fits. Although modelling approaches such as generalised additive models present a simple solution to exploring spatial variation in ecological data, we emphasise the importance of questioning the applicability of such strategies when assessing variation across areas of rapid change such as protected area boundaries.

Assessing the carbon storage value of kelp forest restoration in the Hauraki Gulf Marine Park, New Zealand: Lessons from no-take Marine Protected Areas

Anthropogenic CO2 emissions are one of the principal driving forces of climate change. Climate change leads to systematic changes of ecosystems that cause significant impacts on species interactions, ecosystem processes, and result in profound socio-economic consequences. While carbon offsetting of terrestrial forests and their monetary value are well accepted, the carbon offsetting potential and value of coastal and marine ecosystems (Blue Carbon, BC) remains excluded from the international carbon accounting framework. In this study, we estimated the carbon offsetting value of kelp forests (Ecklonia radiata) against urchin barrens (dominated by crustose coralline algae) using the standing stock biomass as a metric. We propose that standing stock biomass is a crucial next step in introducing BC to the general carbon offsetting framework. Our approach is informed by long-term ecological research conducted in a marine reserve, which highlights the potential of utilizing trophic cascades to limit the dominance of urchin barrens in shallow coastal habitats. We found that the value of carbon standing stock in current kelp forests with reforestation in the Hauraki Gulf Marine Park (HGMP) is worth up to $NZ 7.9 million, based on 2021 carbon market pricing in New Zealand. This simple step towards realizing the value of marine conservation and its multiple benefits to society highlights the missed opportunities when policy and plans do not align with ecology and economics. Including the ocean's contributions to carbon storage is a critical step in using monetization techniques to overcome climate change challenges. Monetizing the carbon offsetting value of kelp forests contributes to establishing funding mechanisms to attract diverse investments in marine ecosystem restoration while providing ecological benefits in ocean governance.

Marine reserve use by a migratory coastal shark, Carcharias taurus

Networks of small no-take marine protected areas (MPAs) are a popular approach to protect mobile marine species at key sites along their migration routes. Understanding how individuals vary in their use of these sites is needed to ensure MPA networks are optimised to offer maximum protection benefits. Using diver-led surveys, coded acoustic tags and a continental-scale collaborative network of acoustic receivers, we investigated variation in the use of three Australian MPAs by aggregating grey nurse sharks, Carcharias taurus. The Wolf Rock MPA was used year-round by C. taurus and as a gestation site, with females spending up to 254 d at the site with 2.2–3.7 year absences between residencies. In contrast, Flat Rock and Cherubs Cave-Henderson Rock MPAs were used as a transitory aggregation site with males and females occurring at the site for 30 min–59 d intervals between June–January, only. Migratory movements ranged up to 1500 km along the coastline, intersected 18 MPAs and/or recognised C. taurus aggregation sites, and connected temperate waters at Montague Island (36.25° S) with that of the southern Great Barrier Reef (23.40° S). Our study demonstrates how local receiver arrays and national collaborative acoustic telemetry networks are powerful tools to reveal use, fidelity and connectivity of MPA networks by marine migratory species. As the east Australian C. taurus population is critically endangered and at particular risk of anthropogenic threats, ongoing monitoring of the species' movement behaviour and complementary management outside protected area boundaries is warranted to assist its protection.

Optimal effort, fish farming, and marine reserve in fisheries management

In this paper, we develop a bioeconomic model to determine an optimal wild catch harvest and freshwater commercial aquaculture production in a lake that uses cages or floating rafts. Although off-bottom aquaculture activities have less impact on the environment compared to on-bottom aquaculture, it has negative externalities. It takes away the fishing area and hence creates pressure in the open-access fishing ground. It also changes the nutrient and ecological composition of the environment. We recommend the implementation of a reserved area to minimize the impact of fishing and aquaculture activities. The reserve also helps in improving the habitat and restocking the fish population which is declining rapidly. We determine the optimal sizes of the aquaculture and reserve and the optimal effort level that maximizes social welfare. We illustrate our findings using numerical simulations and perform an analysis of the optimal solutions with respect to biological and economic parameters involved in the model.

Evidence of rebound effect in New Zealand MPAs: Unintended consequences of spatial management measures

Fish size and fish biomass have been shown to increase inside the borders of Marine Protected Areas (MPAs) after the cessation of fishing. However, the effects of marine protection on fishing fleet behaviour and fish catches outside of MPAs are less well understood. Here we investigated changes in total catch and Catch per Unit Effort (CPUE) of bottom trawlers outside the borders of offshore MPAs in New Zealand. We used Regression Discontinuity in Time (before versus after protection) on both aggregate and individual trawl event data for one Marine Reserve, two Benthic Protected Areas, one Closed Seamount Area and one Marine Mammal Sanctuary. Despite the various forms of protection that reduce the total fishable area, total catch tended to increase after MPA implementation. Yet, there was little evidence that this was due to the net-movement of fish from larger populations within MPA boundaries i.e. spillover. Rather, the increases in catch in the post protection period appeared to be a consequence of changes in the behaviours of commercial fishers. This may be an unintended and previously unreported negative consequence of marine protection that could dampen some of the many benefits of MPAs.

Minimum soak times of Baited Remote Underwater Video needed to assess the status of a coral reef fish community in the northern Gulf of Aqaba

Fishing pressure and other human impacts are increasing throughout much of the Red Sea. We assessed the minimum soak time and status of the coral reef fish community in the Aqaba Marine Park, Jordan prior to its official redesignation as a Marine Reserve in 2020 using baited remote underwater video (BRUV). A total of 86 species from 27 families were recorded in 15 deployments, comprising 60 hours of video. A minimum soak time of 150 minutes was found necessary to sufficiently estimate overall species richness. For richness of commercially valuable families, shorter soak times of 60 minutes were adequate, likely resulting from increased attraction of this largely piscivorous group to the bait plumes. A 30-minute soak time was adequate to assess the maxN of commercially valuable families. Our results indicate that the Aqaba Marine Reserve was overfished prior to its establishment as a reserve, as we recorded no large predators and not a single individual from Carcharhinidae, Haemulidae, Lutjanidae, or Scombridae. Other predator families like Epinephelinae, Lethrinidae, and Carangidae were relatively rare with low maxN. Our results provide a useful point of comparison to assess whether the coral reef fish community will recover as a result of enhanced management action and reduced fishing pressure.

Reconsidering the longline ban in the Galapagos Marine Reserve

In 2000, longline fishing was banned inside the Galapagos Marine Reserve to prevent illegal fishing of sharks and bycatch of endangered, threatened, and protected (ETP) species. Despite local management institutions possess one of the most sophisticated control and surveillance systems in the Eastern Tropical Central Pacific, statistical and anecdotic evidence suggest the longline ban has been ineffective in eradicating illegal, unreported and unregulated (IUU) fishing for the last two decades. This short communication examines the legal, institutional, and socio-economic factors that have prevented the effective implementation of the longline ban and proposes an ecosystem approach to fisheries to maintain bycatch mortality rates below biologically based limits, facilitating the recovery of ETP species while safeguarding a sustainable development of the Galapagos small-scale tuna fishery. Significant investments in science, technology, and innovation are necessary to encourage gradual and adaptive improvements in fishing practices to reduce IUU fishing and bycatch.

HEMATOLOGIC AND BIOCHEMICAL VALUES OF FREE-RANGING HAWKSBILL SEA TURTLES (ERETMOCHELYS IMBRICATA) IN GLOVER'S REEF, BELIZE.

Blood samples were obtained from the dorsal cervical sinus of free-ranging hawksbill sea turtles (Eretmochelys imbricata) collected at Glover's Reef Marine Reserve, 42 km east of the coast of Belize, for hematology and plasma biochemistry analysis. Unknown sex, subadult turtles (N = 32) were sampled in 2013 (n = 22) and 2017 (n = 10). To provide a more robust data set, parameters that did not have statistically significant differences were pooled and treated as a single population. Eleven hematologic parameters were evaluated; of these, five were pooled. Twenty-three plasma biochemical parameters were evaluated; of these, 15 were pooled. The PCV observed in this study (mean 33.44%) was double that observed in two studies of juvenile hawksbills in Dubai (means 17% and 16%), whereas the total WBC count was half that observed in immature and adult hawksbills sampled in the Galápagos (mean 2.91 × 103 versus 5.3 × 103/µl). Total protein and albumin were lower than regionally similar, adult female hawksbills in Brazil (means 3.36 versus 5.45 g/dl and 0.93 versus 2.11 g/dl, respectively). Globulins were higher (mean 2.43 versus 1.06 and 0.5 g/dl), driving the albumin:globulin ratio lower than that observed in two studies of juvenile hawksbills in Dubai (0.4:1 versus 1.1:1 and 1:1, respectively). These findings represent a geographically distinct population from previous reports, highlight the variability in blood parameters from disparate populations, and reaffirm the vital importance of considering a multitude of variables when interpreting reptilian blood values. The similarities in the majority of values observed in 2013 and 2017 provide confidence in the stability of these parameters in this population.

Strategy for Establishing Indonesian Marine Reserve Components to Face China's Gray Zone Operations in North Natuna Sea

Strategy for Establishing Indonesian Marine Reserve Components to Face China's Gray Zone Operations in North Natuna Sea

A dynamic game model for no-take marine reserves

Representing about 8% of the world’s oceans, marine protected areas (MPAs) are effective instruments for mitigating the damage that overfishing can do to ecological and economic systems. Yet, less than 2% of the ocean is proclaimed an exclusive no-take zone. Expecting their number and size to increase significantly in the coming years, meticulous implementation of MPAs is central to their success. Using a dynamic game model we explore the impact of designated no-take marine reserves on fish stock and on fishing strategies. Our findings suggest that optimality can be achieved in a context of a combination of three marine zones, i.e., an open access fishery, a marine protected area and a fish bank. Our methodology consists of considering an infinite time horizon discrete fishing game with a migratory species between the three regions. We analyze fishing strategies and characterize the model equilibria for different behaviors, the fully non-cooperative scheme, the social optimum and the cartel setting. Our analytical results are supported by the use of a numerical simulation that compares different scenarios, including the current state of the world in contrast to different sizes of MPAs and fish bank areas.

Potential solutions to environmental conflict on exploitation of fish stocks in palk strait among fishermen of India and Sri Lanka

Illegal catching of fish stocks beyond the borders of India and Sri Lanka by violating the International Maritime Boundary Line (IMBL) by the fishing communities of both countries has become a major international direct environmental conflict between both nations. Overexploitation of natural resources is a keystone environmental problem. It has been reported that Indian fishermen are stealing fish catch worth many millions of US dollars annually from Sri Lankan coastal waters. The bilateral agreements of 1974 and 1976 are frequently violated. The heavy use of trawlers that are not permitted to fish on coastal seas and the use of internationally banned bottom sea nets by Indian poachers are major threats to the coastal resources of north Sri Lanka. Trawlers catch fish flocks unselectively; the catch may include several non-targeted species and juvenile stages of fish, which is leading to species extinction. Arresting and imprisoning of fishermen by coastal guards of both countries (and collecting penalties) continue, and this is an unsustainable way of handling the issue. Sri Lanka has banned bottom trawling since the 6th of July 2017, which is a sustainable solution and beseeched possible greener solutions such as creating awareness, sensitizing fishermen, and promoting the use of GPS navigation, and also provoked conventional solutions such as monitoring or patrolling, which often lead to imprisonment and penalties for trespassing and seizing of fishing trawlers. Restorative solutions such as coral restoration, mangrove restoration, implantation of artificial reefs, and establishing mutually beneficial ‘no catch zone’ along the IMBL and marine reserves (or marine protected areas) by both nations may facilitate preventing the deterioration of fish stocks and ensuring their revival in the region. Above all, if this illegal catching continues, the availability of fish stocks in the Palk Strait region in the next ten years will be in question.

Shifting the conservation Overton window

Shifting the conservation Overton window

Seasonal and diel habitat use of blue marlin Makaira nigricans in the North Atlantic Ocean

Abstract Knowledge of blue marlin, Makaira nigricans, movement patterns across a range of spatiotemporal scales is important for understanding the ecology of this epipelagic fish, informing responsible management strategies, and understanding the potential impacts of a changing ocean climate to the species. To gain insight into movement patterns, we analyzed data from 66 blue marlin satellite-tagged between 2001 and 2021 throughout the North Atlantic. We recorded migrations connecting west and east Atlantic tagging locations, as well as long-term residency within small sub-regions. Blue marlin showed a pattern of latitudinal migration, occupying lower latitudes during cooler months and higher latitudes in warmer months. Diving data indicate blue marlin primarily inhabited a shallow vertical habitat with deeper diving associated with higher sea surface temperatures and dissolved oxygen content. Consistent patterns in diel vertical habitat use support the hypothesis that these fish are visual hunters, diving deeper during the day, as well as dawn, dusk, and full moon periods. The wide-ranging movements of blue marlin indicate that traditional spatial management measures, such as static marine reserves, are unlikely to be effective in reducing the fishing mortality of this species. Longer tag deployment durations are required to delineate its annual and multi-annual migratory cycle.