Decimation of a population of the endangered species Scutellastra mexicana (Broderip and Sowerby, 1829) (Mollusca,Gastropoda) in the Marías Island (Eastern Ocean Pacific) Biosphere Reserve

1. Scutellastra mexicana is the largest known patellid limpet species and probably is one of the most endangered marine invertebrates.
2. The species was once distributed along the American Pacific coast from Mexico to Peru, but their large size (up to 35 cm long) and easy accessibility (shallow sublittoral), made it very vulnerable to human collection and now is extinct on most of the mainland Mexican coast.
3. In August 2017, a large population of this species was found on María Cleofas island, off the coast of west‐central Mexico (Marías Archipelago, Pacific Ocean). This constitutes the only report of a population of this species since 1988.
4. A total of 808 adult individuals of up to 26 cm in length and 20 cm in width were estimated, together with the presence of juveniles, suggesting that it is a self‐sustaining population. The population was monitored in August 2017 and August 2018.
5. Although the species is under the category ‘Special Protection’ in the General Mexican Wild Law, and that María Cleofas island is a Biosphere Reserve, fishermen that operate with impunity in the area decimated the limpet population within a year of its discovery. Abundance in the shallowest area decreased significantly from 120 individuals per transect (65 m long and 2.75 m wide) in August 2017 to 48 individuals in August 2018, and the estimated adult population decreased from 808 to 304 limpets.
6. Neither passive national conservation policies nor local practices have reduced current threats to biodiversity and resource depletion in Marías Archipelago. Protected areas like this are ‘paper parks’—parks in name only—because there is no active conservation strategy or protection of marine species.

     

The protection effects of marine protected areas on exploited molluscs from an oceanic archipelago

1. Limpets are one of the most successful intertidal algal grazers in the north‐eastern Atlantic. They provide valuable ecosystem services, playing a pivotal role in maintaining rocky shore ecological balance and have an important economic value, being subject to high levels of exploitation in several oceanic archipelagos. Limpets represent one of the most profitable economic activities of small‐scale fisheries in the Madeira archipelago. However, limpets are extremely vulnerable to anthropogenic impacts, such as overharvesting, habitat fragmentation, and pollution.
2. The protection effects and the effectiveness of marine protected areas (MPAs) on the population dynamics of two historically highly exploited limpet species, Patella aspera and Patella candei, were analysed through a comparative study of size, reproduction, and biomass in the Madeira archipelago.
3. The effects of protection from MPAs on limpet populations resulted in a differential increase on size at first maturity, shell size, and capture per unit effort according to the degree of protection.
4. Old and enforced MPAs showed the best‐preserved limpet populations in the study area, and both variables (age and enforcement) best explained the observed variability among the MPAs studied.
5. A thorough and multidisciplinary study is necessary to obtain a reliable picture of commercial stocks of the two targeted species (P. aspera and P. candei). Genetic analysis and studies on the food source of limpets may shed light to develop integrative conservation strategies.

     

Population genetic divergence of bonnethead sharks Sphyrna tiburo in the western North Atlantic: Implications for conservation

1. Sharks are a priority for conservation because numerous species, including small-sized coastal species, are being heavily exploited by commercial and recreational fisheries. Understanding the genetic population structure of sharks is key to effective management, maximizing their evolutionary potential in a rapidly changing environment and preventing population declines.
2. Limited dispersal is an important factor promoting population divergence for several coastal shark species. The genetic variation in 14 microsatellite loci and 21,006 single nucleotide polymorphisms genotyped using restriction-site-associated DNA sequencing was analysed to assess the genetic structure of the bonnethead shark, Sphyrna tiburo, in the western North Atlantic.
3. Genetic differences were identified among three well-defined regions: the western Florida coast, the south-eastern US Atlantic coast, and the southern Gulf of Mexico. Results support previous studies based on mitochondrial DNA sequences in defining differences among these regions and suggest limitations of bonnethead sharks in routinely performing long-distance migrations.
4. The limited connectivity among regions explains the pattern of genetic divergence but also reported divergence at the species/subspecies level. These genetically discrete bonnethead populations have independent evolutionary histories that may include local adaptations to specific areas.
5. Bonnethead sharks are currently managed as two stocks in the USA owing to recent genetic, tagging, and life history studies; however, no stock assessments or management plans exist for Mexico. These results not only serve to reinforce US management strategies and provide critical data about the extent of gene flow and sex dispersal among populations, but also begin the process of effective management in the waters of Mexico to ensure the long-term productivity and resilience of this species. With an absence of gene flow between populations from US waters and the southern Gulf of Mexico, there is a need for management plans based upon independent biological and population dynamics data since limited or no opportunities for populations to interchange individuals may occur to re-establish population viability.

     

Identifying critical foraging habitats of the green turtle (Chelonia mydas) along the Pacific coast of the Baja California peninsula,Mexico

• 1. The conservation of highly mobile and migratory species remains one of the most serious challenges to resource managers.
• 2. Intense mortality of immature green turtles has been identified at principal developmental–feeding habitats in Baja California, and is considered a great threat to the stability of the eastern Pacific population. Thus, coastal lagoons of the Baja California peninsula, such as Bahía Magdalena, have been identified as high priority areas for their protection.
• 3. Conservation efforts to date have focused on creating a sea turtle refuge in the northwestern part of the bay, but this area may not be sufficient for protecting all of the critical feeding areas used by green turtles.
• 4. The diet of green turtles was investigated through analysis of digestive tract contents from 24 green turtles that were drowned incidentally in fishing nets at feeding grounds in Bahía Magdalena and adjacent areas along the Pacific coast of the Baja California peninsula, Mexico.
• 5. Mean straight carapace length (SCL) differed significantly between localities: mean: 55.5 cm (range: 47.7–76.9 cm, n=11) in Bahía Magdalena; mean: 67.7 >cm (range: 49–87 cm, n=11) in adjacent coastal waters.
• 6. Green turtle diet consisted largely of marine algae and seagrasses, but food items varied spatially. The red algae Gracilaria pacifica, Gracilariopsis lemaneiformis and Hypea johnstonii were the most abundant diet items inside Bahía Magdalena, and the seagrass Phyllospadix torreyi was the most commonly ingested food in coastal areas outside of the bay.
• 7. Results indicate that green turtles utilize spatially distinct foraging habitats within this region. Therefore, it is recommended that any design of protected areas for sea turtles in Bahía Magdalena should consider a regional approach instead of a local approach, taking into account the most important feeding areas used by green turtles at different life stages.

Copyright © 2005 John Wiley & Sons, Ltd.     

Migratory connectivity and local site fidelity in red knots on the southern Pacific coast of South America

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Artificial portable plates: A brand new method for assisted colonization of an endangered marine invertebrate,Patella ferruginea

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Using landing statistics and fishers’ traditional ecological knowledge to assess conservation threats to Pacific goliath grouper in Colombia

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Genetic diversity of immature Kemp's ridley (Lepidochelys kempii) sea turtles from the northern Gulf of Mexico

1. The Kemp’s ridley (Lepidochelys kempii) is the world’s most endangered sea turtle species. Predominately nesting at only one beach in Mexico, this species declined to an estimated 300 females in the mid-1980s. Conservation efforts in the United States and Mexico, including a head start programme in southern Texas in which hatchlings were reared in captivity for several months before being released into the wild, resulted in the recovery of this species.
2. Although genetic data have previously been used to assess the success of the head start programme and dispersal of individual adults, data on immature turtles sampled at foraging areas and adult females sampled at the main nesting beach in Mexico are lacking. Genetic characterization of immature individuals is important for understanding recruitment, survival, and population demography, while genetic data on individuals from Mexico are essential for understanding dispersal and overall genetic diversity in this species.
3. To address these gaps, mitochondrial DNA data were collected from 106 immature individuals sampled at four different foraging sites in the northern Gulf of Mexico and from 18 nesting females at the primary nesting beach in Mexico.
4. Two previously unknown mitochondrial DNA haplotypes were discovered among the immature individuals.
5. Except for these two new haplotypes, the genetic diversity of immature individuals in the northern Gulf of Mexico closely corresponds to that of adults sampled in Mexico, which suggests that much of the diversity within the nesting population can be found among immature animals dispersing to foraging grounds, including locations in the northern Gulf of Mexico.
6. Continued monitoring of the genetic variation of different life stages of this species across its distribution range will help assess the success of conservation programmes by ensuring the maintenance of genetic diversity and representation of this diversity across the species’ distribution range.

     

The potential of temporary shelters to increase survival of the endangered Mexican axolotl

1. Amphibian populations worldwide are in decline. Proactive conservation techniques such as translocations into created and restored wetlands have gained popularity in recent years but may fail owing to high predation and low environmental adaptability.
2. The Mexican axolotl (Ambystoma mexicanum), affected by rapid urbanization, is now possibly extinct in the wild despite millions living in captivity throughout the world.
3. The aim of this study was to explore whether ponds from an artificial wetland can function as temporary shelters for a viable population of axolotls that could be re-introduced into their native ecosystem in Xochimilco once it is restored.
4. Egg-laying and hatching of 11 unique axolotl pairs placed into reproductive enclosures and larval survival to 7 weeks and up to 12 months were examined. Physicochemical and biological parameters were estimated and compared among ponds.
5. The results from this study are encouraging as they suggest that two ponds have adequate conditions for axolotls to reproduce and for larvae and juveniles to survive.

     

Potential distribution and population trends of the smalltail shark Carcharhinus porosus inferred from species distribution models and historical catch data

1. Updated distribution ranges are crucial for conservation status assessments. Comprehensive analyses combining published literature and available data on historical catches and species distribution models (SDMs) are effective tools that could improve the prediction of more realistic scenarios for some species, especially those with limited information available and facing multiple threats.
2. The present study aimed at generating an updated distribution for the smalltail shark Carcharhinus porosus, one of the most threatened and understudied shark species of the western Atlantic Ocean. Estimates of the key areas for this species conservation based on the SDMs, and trends in catch probabilities throughout its distribution range are provided.
3. Four algorithms (BIOCLIM, Domain, Mahalanobis, and Maximum Entropy) were used to model the distribution of C. porosus and calculate its habitat suitability based on marine environmental variables. To assess historical catch probability trends, we built a generalized linear model from published and grey literature data. This analysis was used to estimate catch probability as an indication of population trends.
4. SDMs suggest that the northern coast of South America (NCSA) harbours the most suitable habitats for C. porosus in the world, which was expected given its historically high catch rate in this region. In addition, there was a continuously declining catch probability trend starting in the 1970s. However, the decline was smaller for the NCSA as compared with the Gulf of Mexico and the eastern South America coast.
5. Results indicate that the NCSA should be considered the currently most important area in the world for this species conservation. Furthermore, the lack of data throughout Central and South American marine regions hampers the evaluation of extinction risk throughout its updated distribution. Thus, research in these areas is urgently required for a more comprehensive conservation status assessment.

     

New records of the distribution and conservation status of the endangered limpet Patella ferruginea in Sardinia (Italy,W Mediterranean)

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The thin edge of the wedge: Extremely high extinction risk in wedgefishes and giant guitarfishes

1. The process of understanding the rapid global decline of sawfishes (Pristidae) has revealed great concern for their relatives, the wedgefishes (Rhinidae) and giant guitarfishes (Glaucostegidae), not least because all three families are targeted for their high‐value and internationally traded ‘white’ fins.
2. The objective of this study was to assess the extinction risk of all 10 wedgefishes and six giant guitarfishes by applying the International Union for Conservation of Nature (IUCN) Red List Categories and Criteria, and to summarize the latest understanding of their biogeography and habitat, life history, exploitation, use and trade, and population status. Three of the 10 wedgefish species had not been assessed previously for the IUCN Red List.
3. Wedgefishes and giant guitarfishes have overtaken sawfishes as the most imperilled marine fish families globally, with all but one of the 16 species facing an extremely high risk of extinction through a combination of traits: limited biological productivity; presence in shallow waters overlapping with some of the most intense and increasing coastal fisheries in the world; and overexploitation in target and by‐catch fisheries, driven by the need for animal protein and food security in coastal communities and the trade in meat and high‐value fins.
4. Two species with very restricted ranges, the clown wedgefish (Rhynchobatus cooki) of the Malay Archipelago and the false shark ray (Rhynchorhina mauritaniensis) of Mauritania, may be very close to extinction.
5. Only the eyebrow wedgefish (Rhynchobatus palpebratus) is not assessed as Critically Endangered, with it occurring primarily in Australia where fishing pressure is low and some management measures are in place. Australia represents a ‘lifeboat’ for the three wedgefish and one giant guitarfish species occurring there.
6. To conserve populations and permit recovery, a suite of measures will be required that will need to include species protection, spatial management, by‐catch mitigation, and harvest and international trade management, all of which will be dependent on effective enforcement.

     

Are there life-history constraints on restoration of the endangered limpet Patella ferruginea (Mollusca,Gastropoda) in the northern Mediterranean Sea?

1. Effectiveness of restoration/repopulation measures may be strongly hindered by the ability of the target species to cope with the environmental conditions of the receiving area.
2. Although a species has been reported previously for a given area, the environmental conditions and human pressures may have changed, potentially making any restoration attempt ineffective. Evidence is provided showing that the endangered ferruginous limpet Patella ferruginea can complete its reproductive cycle in the northernmost sector of the western Mediterranean.
3. This supports the idea that the reintroduction and the strict protection of P. ferruginea in the extreme north of its historical geographic range could be effective for the recovery of the species in this area and ultimately the establishment of reproductively viable and stable populations.
4. Verification of gonadal maturation of specimens experimentally established on the Gulf of Genoa (Ligurian Sea) coastline, as well as evidence of sex change in one individual (the first outside the Alboran Sea), provides further support of the potential for individuals to complete their reproductive cycle in this area.
5. The results support the potential of actions for the restoration of viable populations of the species along the Ligurian coasts through the introduction of juveniles obtained exclusively by aquaculture techniques, in order to mitigate any impact on donor sites.

     

Modelling the potential distribution of two tropical freshwater fish species under climate change scenarios

1. Climate change is causing shifts in the distribution patterns of freshwater fish at various spatio-temporal scales. Tropical freshwater fish are vulnerable, especially in areas where a high impact of climate change is predicted; thus, there is an increasing need to predict these shifts to determine conservation and adaptation strategies.
2. Ecological niche models offer a reliable way to predict the effects of climate change on species distribution. Potential shifts in the distribution of tropical fish were tested under two scenarios (4.5 – moderate and 8.5 – extreme) with three general circulation models for years 2050 and 2070 using maximum entropy software using as models two predatory species – the tropical gar Atractosteus tropicus and the giant cichlid Petenia splendida.
3. The potential distribution of both species was associated with warm and humid–sub-humid conditions. Future projections showed a higher availability of suitable areas for both species resulting from the expansion of warmer conditions in the middle and upper basins of the Central American mountain range and centre of the Yucatan Peninsula.
4. Ecological niche models of keystone or umbrella species such as A. tropicus and P. splendida could be useful to support conservation plans of protected areas. The potential distribution of both species covers areas of high suitability including six important biosphere reserves in Mexico, three protected areas in Guatemala and part of the Mesoamerican biological corridor.
5. Despite the potential expansion of the present distribution range suggested by the models, it is important to consider the biological and ecological requirements of the species and the ecological implications of these potential shifts in distribution. Both scenarios could have several implications at genetic, population, and ecosystem levels.

     

Risk assessment for the Mexican freshwater crayfish: the roles of diversity,endemism and conservation status

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Involving local people in the conservation of the critically endangered freshwater turtle Dermatemys mawii in southern Mexico

1. The Central American river turtle Dermatemys mawii is one of the most endangered species in the world, and continues to decline. In Mexico, this turtle is legally protected but, in the rural areas where it is found, local people are not aware of why it is important to conserve it.
2. This study confirmed that D. mawii inhabits lakes in southern Mexico, and that these areas are among the last refuges for this species inside and outside protected areas in the wild.
3. A lack of knowledge about its endangered status among local people means that a strategy of environmental education is needed.

     

Unravelling the complex habitat use of the white mullet,Mugil curema,in several coastal environments from Neotropical Pacific and Atlantic waters

1. The white mullet, Mugil curema, is a widely distributed euryhaline species, the migratory behaviour of which is poorly understood. The objective of this work was to study the large-scale habitat use of this species for the first time. Several environments were considered, such as euryhaline and hypersaline lagoons, the sea, and a river, distributed in the Central Pacific (Mexico) and Atlantic (Gulf of Mexico, Caribbean Sea-Venezuela, and north-eastern Brazil).
2. Otolith core-to-edge Sr/Ca ratios of 163 fish, determined by laser ablation inductively coupled plasma mass spectrometry, were used to study the salinity-habitat migration history of the fish. Fish from Mexico (Tamiahua Lagoon, n = 4; Alvarado Lagoon, n = 2), Venezuela (n = 1), and Brazil (n = 12) (11.1% of the total) showed high Sr/Ca values at early life stages and were classified as marine estuarine opportunists. Two specimens (from Alvarado Lagoon and Balsas River, Mexico) showed Sr/Ca values consistently below the high salinity guide value (salinity < 33.5). For the rest of the fish (87.1%), the Sr/Ca ratio suggested a displacement from the estuary towards the sea or hypersaline environments, and so these fish were classified as estuarine migrants.
3. A change-point analysis identified six individuals with a single stable otolith Sr/Ca signature through ontogeny (three from Brazil, one from Venezuela, and two from Tamiahua Lagoon, Mexico), suggesting limited displacement between environments with different salinities. The rest of the individuals showed between two and 10 changes in stable Sr/Ca signatures (mean = 4.07 ± 1.85). The highest number of changes in Sr/Ca ratio (4.87 ± 1.1) was found in fish from Laguna Madre (Mexico) and the lowest was found in fish from Brazil (3.27 ± 1.70) (H = 19.8, p = 0.002).
4. Otolith Sr/Ca time series suggest that the migratory estuarine pattern is the most common throughout the study area. This work highlights that the sustainable use of M. curema depends on the conservation of estuaries and the corridors between them and other environments such as lagoons, rivers, mangroves and the sea.

     

Fisheries and conservation assessment of sharks in Pacific Panama

1. In Panama, shark fisheries were initially developed in the 1980s and progressively increased in production in the 1990s mainly due to the high demand for shark fins and meat from the international Asian market. Since then, and despite the exploitation rate (average 3,514 t year^–1) and endangered status of some species, shark fisheries have seldom been studied, and official statistics are general or incomplete and not suitable for the development of appropriate conservation and management strategies.
2. To understand the dynamics of shark fisheries in Panama, field surveys were conducted between 2007 and 2009 at several landing ports of small‐scale and industrial fisheries, at fish processing plants and on‐board fishing vessels in Pacific Panama, where most of the fishing vessels of the country operate.
3. In general, it was found that the artisanal and industrial fisheries of the Pacific coast of Panama regularly exploit at least 18 species of sharks, which are also being exploited by neighbouring countries in the eastern Pacific, suggesting the importance of coordinated conservation initiatives across the multiple jurisdictions. A large number of the individuals caught were immature, implying a certain level of impact on recruitment rates. This pattern was particularly evident in species such as Sphyrna lewini, for which immature individuals represented at least 99% and 63% of the total catch by small‐scale and industrial fisheries, respectively. Catch per unit of effort analyses showed that Carcharhinus and Sphyrna species were the most exploited (representing ~80% of the catches) by industrial fisheries in Panama between 2006 and 2009, suggesting that fishery management should provide special attention to these groups.
4. It is expected that the information presented here provides a baseline to develop new regulations, including the implementation of annual quotas and fishing seasons and the protection of nursery areas, for the long‐term sustainability and conservation of sharks in Panama.

     

Is the establishment of MPAs enough to preserve endangered intertidal species? The case of Patella ferruginea in Mal di Ventre Island (W Sardinia,Italy)

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Genetic structure,origin, and connectivity between nesting and foraging areas of hawksbill turtles of the Yucatan Peninsula: A study for conservation and management

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