New findings into the genetic population structure of two commercially valuable and threatened sharks, Mustelus mustelus (Linnaeus, 1758) and M. punctulatus (Risso, 1827), allow refining management strategy in the Central Mediterranean Sea

Frontiers in Marine Science, Journal Year: 2025, Volume and Issue: 12

Published: Feb. 7, 2025

Elasmobranch species are the direct or accidental catch of fisheries and can have a commercial importance. In Mediterranean Sea, long-term period overfishing brought several demersal elasmobranchs to be depleted threatened by extinction, due vulnerability related their life history traits. such exploited species, information on genetic diversity connectivity is lacking should collected identify management units. this study, we focused two smooth-hound Mustelus (Linnaeus, 1758) M. punctulatus (Risso, 1827), whose abundance distribution showed decline at regional level in last century. Thanks an opportunistic yet extensive sampling, obtained largest subregional collection specimens for analysis so far. total, 86 214 mustelus were between 2016 2020 Adriatic Sea Strait Sicily. We assessed population structure typing 17 microsatellites sequencing part mitochondrial control region both species. observed substantial nuclear when accounting geographical sampling area Our results indicate presence least stocks each species: one Sicily other Sea. This study provides valuable data that integrated into broader approach define units, improving development effective strategy these Central

Language: Английский

---

Genomic Assessment of Australian White Sharks (Carcharodon carcharias) Challenges Previous Evidence of Population Subdivision

Diversity and Distributions, Journal Year: 2025, Volume and Issue: 31(2)

Published: Feb. 1, 2025

ABSTRACT Aim The white shark ( Carcharodon carcharias ) is one of the world's largest and most recognisable marine predators but has suffered significant declines since mid‐twentieth century. Conservation efforts remain complicated by persistent knowledge gaps associated with biology ecology, including biological connectedness populations. We re‐assess patterns population genetic structure in Australian sharks, where two subpopulations—eastern southern‐western—are currently recognised based on previous animal tracking assessments. Methods Population genomic analyses are performed using tissues from ~650 individual sharks ~7000 single nucleotide polymorphism (SNP) loci generated through reduced genome representation sequencing. test for evidence relatedness among eastern southern Australia use simulations to assess likely strength inter‐generational migration between regions. Results This study challenges current paradigm showing a lack Australia. These findings further supported kinship indicating high levels intergenerational Consistent recent reports Australia, we also detected juvenile subadult estimated overall effective size Ne be less than 500 individuals. Furthermore, provide potential reduction over last generations. Main Conclusions Overall, these highlight need consider this revised estimate when discussing management conservation species. Our results raise concerns highlighting risks inbreeding, reductions fitness resilience. discuss research importance ongoing monitoring.

Language: Английский

---

From rivers to ocean basins: The role of ocean barriers and philopatry in the genetic structuring of a cosmopolitan coastal predator

Ecology and Evolution, Journal Year: 2023, Volume and Issue: 13(2)

Published: Feb. 1, 2023

Abstract The Bull Shark ( Carcharhinus leucas ) faces varying levels of exploitation around the world due to its coastal distribution. Information regarding population connectivity is crucial evaluate conservation status and local fishing impacts. In this study, we sampled 922 putative Sharks from 19 locations in first global assessment structure cosmopolitan species. Using a recently developed DNA‐capture approach (DArTcap), samples were genotyped for 3400 nuclear markers. Additionally, full mitochondrial genomes 384 Indo‐Pacific sequenced. Reproductive isolation was found between across ocean basins (eastern Pacific, western Atlantic, eastern Indo‐West Pacific) with distinct island populations Japan Fiji. appear maintain gene flow using shallow waters as dispersal corridors, whereas large oceanic distances historical land‐bridges act barriers. Females tend return same area reproduction, making them more susceptible threats an important focus management actions. Given these behaviors, insular populations, such Fiji, may instigate decline that cannot readily be replenished by immigration, which can turn affect ecosystem dynamics functions. These data also supported development genetic panel ascertain origin, will useful monitoring trade fisheries products assessing population‐level impacts harvest.

Language: Английский

---

Connections Across Open Water: A Bi‐Organelle, Genomics‐Scale Assessment of Atlantic‐Wide Population Dynamics in a Pelagic, Endangered Apex Predator Shark (Isurus oxyrinchus)

Evolutionary Applications, Journal Year: 2025, Volume and Issue: 18(1)

Published: Jan. 1, 2025

Large-bodied pelagic sharks are key regulators of oceanic ecosystem stability, but highly impacted by severe overfishing. One such species, the shortfin mako shark (Isurus oxyrinchus), a globally widespread, migratory predator, has undergone dramatic population reductions and is now Endangered (IUCN Red List), with Atlantic Ocean in particular assessed fishery managers as overfished need urgent, improved management attention. Genomic-scale assessments for this apex predator species have not been previously available to inform planning; thus, we investigated genetics across using bi-organelle genomics approach. Complete mitochondrial genome (mitogenome) sequences genome-wide SNPs from distributed revealed contrasting patterns structure marker types. Consistent species' long-distance capabilities, showed high connectivity panmixia overall. In contrast, there was matrilineal genetic Northern Southern Hemispheres, suggesting at least large regional-scale female philopatry. Linkage disequilibrium network analysis indicated that makos possess chromosomal inversion occurs wide, feature may be informative evolutionary investigations concerning adaptations global history iconic species. Mitogenome diversity compared other elasmobranchs mitogenome level, nuclear two other, SNPs. These results support efforts on versus Hemisphere scales preserve their distinctiveness. The overall comparative findings provide baseline future monitoring diversity, called United Nations Convention Biological Diversity, cautious optimism regarding health recovery potential if further declines can halted.

Language: Английский

---

Informing the spatial management of Silky Shark (Carcharhinus falciformis) in the Eastern Pacific Ocean

Reviews in Fish Biology and Fisheries, Journal Year: 2025, Volume and Issue: unknown

Published: April 30, 2025

Language: Английский

---

Commercial sharks under scrutiny: Baseline genetic distinctiveness supports structured populations of small-spotted catsharks in the Mediterranean Sea

Frontiers in Marine Science, Journal Year: 2023, Volume and Issue: 10

Published: Feb. 24, 2023

The present study, based on microsatellite markers, describes a population genetic analysis of the small-spotted catshark Scyliorhinus canicula (Linnaeus, 1758), representing one most abundant and commonly caught cartilaginous fishes in Mediterranean Sea adjacent areas. analyses were performed to unravel features (variability, connectivity, sex-biased dispersal) their relative geographic populations, both at small (around coast Sardinia, Western Sea) larger spatial scale (pan-Mediterranean level between Atlantic Ocean Sea). Individual clustering, multivariate variance rejected hypothesis homogeneity, with significant differences mainly within Eastern basins, as well NE Ocean. In detail, our results seem confirm that Strait Gibraltar could not represent complete barrier exchange individuals Sea. latter area, complex structuring for S. was found. Apart from among Western, Adriatic sites, basin catsharks around Sardinian waters are strongly differentiated all others (both eastern Tyrrhenian southernmost part Algerian basin) demographically stable. Several possible mechanisms, biological abiotic (e.g., migratory behavior, waterfronts, oceanographic discontinuities), discussed here explain peculiar characteristics. Overall, data presented, local regional level, baseline information, useful temporal monitoring assess effects or future fishing/management/conservation measures.

Language: Английский

---

Local adaptive variation in a highly migratory fish: The smooth hammerhead shark Sphyrna zygaena

Ecological Genetics and Genomics, Journal Year: 2024, Volume and Issue: 31, P. 100233 - 100233

Published: Feb. 22, 2024

Language: Английский

---

Genomic evidence indicates small island-resident populations and sex-biased behaviors of Hawaiian reef Manta Rays

BMC Ecology and Evolution, Journal Year: 2023, Volume and Issue: 23(1)

Published: July 8, 2023

Abstract Background Reef manta rays ( Mobula alfredi ) are globally distributed in tropical and subtropical seas. Their life history traits (slow growth, late maturity, low reproductive output) make them vulnerable to perturbations therefore require informed management strategies. Previous studies have reported wide-spread genetic connectivity along continental shelves suggesting high gene flow continuous habitats spanning hundreds of kilometers. However, the Hawaiian Islands, tagging photo-identification evidence suggest island populations isolated despite proximity, a hypothesis that has not yet been evaluated with data. Results This island-resident was tested by analyzing whole mitogenome haplotypes 2048 nuclear single nucleotide polymorphisms (SNPs) between M. (n = 38) on Hawaiʻi Island Maui Nui (the 4-island complex Maui, Molokaʻi, Lānaʻi Kahoʻolawe). Strong divergence Φ ST 0.488) relative genome-wide SNPs (neutral F 0.003; outlier 0.186), clustering mitochondrial among islands provides robust female reef strongly philopatric do migrate these two groups. Combined restricted male-mediated migration, equivalent male moving every 2.2 generations (~ 64 years), we provide significantly demographically isolated. Estimates contemporary effective population size N e 104 (95% CI: 99–110) 129 122–136) Nui. Conclusions Concordant from photo identification studies, results indicate small, genetically-isolated resident populations. We hypothesize due Mass Effect, large sufficient resources support populations, thereby making crossing deep channels separating groups unnecessary. Small size, diversity, k-selected region-specific anthropogenic threats, which include entanglement, boat strikes, habitat degradation. The long-term persistence Islands will island-specific

Language: Английский

---

Demographics and dynamics of the world’s largest known population of oceanic manta rays Mobula birostris in coastal Ecuador

Marine Ecology Progress Series, Journal Year: 2022, Volume and Issue: 700, P. 145 - 159

Published: Oct. 10, 2022

Information on the life history and demographics of oceanic manta rays Mobula birostris remains scarce. Using photo-ID data, we describe demographic structure, population size, possible environmental drivers seasonal occurrence M. at Isla de la Plata Bajo Copé, Ecuador. We identified a total 2803 individuals from 3322 encounters over period 14 yr (2005-2018). The sampled these sites was significantly biased towards males (sex ratio 1F:1.67M) only 12.9% were resighted. used mark-resight models to estimate parameters population, including superpopulation survival probability, entry/recruitment detection probability. also evaluated how related predictors, such as El Niño-Southern Oscillation (ENSO), sea surface temperature (SST), chlorophyll (chl a) . Mark-resight analyses indicated that SST, chl , time, sex, but not ENSO, important predictors estimated parameters. Entry probability peaked in 2012, which coincided with lowest SST highest concentrations. best-fit model size 22316 individuals, annual abundances 949-7650 females 5226-9340 males. Localised sampling this highly mobile species limits interpretations analyses, provides lower bounds for abundance indicate coastal Ecuador Peru is likely largest world.

Language: Английский

---

Philopatry influences the genetic population structure of the blacktip shark (Carcharhinus limbatus) at multiple spatial scales

Molecular Ecology, Journal Year: 2023, Volume and Issue: 32(18), P. 4953 - 4970

Published: Aug. 11, 2023

Abstract Understanding how interactions among microevolutionary forces generate genetic population structure of exploited species is vital to the implementation management policies that facilitate persistence. Philopatry displayed by many coastal shark can impact gene flow and selection, has direct implications for spatial scales management. Here, blacktip ( Carcharhinus limbatus ) was examined using a mixed‐marker approach employing mitochondrial control region sequences 4339 SNP‐containing loci generated ddRAD‐Seq. Genetic variation assessed young‐of‐the‐year sampled in 11 sites waters United States western North Atlantic Ocean, including Gulf Mexico. Spatial environmental analyses detected 68 nuclear putatively under enabling separate assessments neutral adaptive structure. Both SNP data indicated three genetically distinct units—the Atlantic, eastern Gulf, Gulf—that align with regional stocks suggest philopatry males females. Heterogeneity at associated temperature salinity, observed within units, suggesting local adaptation. Furthermore, five pairs siblings were identified same site across timescales corresponding female reproductive cycles. This indicates females re‐used parturition, which potential sorting neighbouring sites. The results demonstrate differential impacts varying highlight importance conserving essential habitats maintain sources may buffer against change.

Language: Английский

---