The use of multibeam sonar mapping techniques to refine population estimates of the endangered white abalone (Haliotis sorenseni)

Multibeam sonar mapping techniques provide detailed benthic habitat information that can be combined with the data on species-specific habitat preferences to provide highly accurate calculations of populations in a particular area. The amount of suitable habitat available for the endangered white abalone (Haliotis sorenseni) was quantified to aid in obtaining an accurate estimate of the number of remaining individuals at two offshore banks and one island site off the coast of southern California. Habitat was mapped by using multibeam sonar survey techniques and categorized by using rugosity and topographic position analysis. Abalone densities were evaluated by using a remotely operated vehicle and video transect methods. The total amount of suitable habitat at these three sites was far greater than that previously estimated. Therefore, although present estimates of white abalone densities are several orders of magnitude lower than historic estimates, the total population is likely larger than previously reported because of the additional amount of habitat surveyed in this study.

Estimating species and size composition of rockfishes to verify targets in acoustic surveys of untrawlable areas

Rockfish (Sebastes spp.) biomass is difficult to assess with standard bottom trawl or acoustic surveys because of their propensity to aggregate near the seafloor in highrelief areas that are inaccessible to sampling by trawling. We compared the ability of a remotely operated vehicle (ROV), a modified bottom trawl, and a stereo drop camera system (SDC) to identify rockfish species and estimate their size composition. The ability to discriminate species was highest for the bottom trawl and lowest for the SDC. Mean lengths and size distributions varied among the gear types, although a larger number of length measurements could be collected with the bottom trawl and SDC than with the ROV. Dusky (S. variabilis), harlequin (S. variegatus), and northern rockfish (S. polyspinis), and Pacific ocean perch (S. alutus) were the species observed in greatest abundance. Only dusky and northern rockfish regularly occurred in trawlable areas, whereas these two species and many more occurred in untrawlable areas. The SDC was able to resolve the height of fish off the seafloor, and some of the rockfish species were observed only near the seafloor in the acoustic dead zone. This finding is important, in that fish found exclusively in the acoustic dead zone cannot be assessed acoustically. For these species, methods such as bottom trawls, long-lines, or optical surveys using line transect or area swept methods will be the only adequate means to estimate the abundance of these fishes. Our results suggest that the selection of appropriate methods for verifying targets will depend on the habitat types and species complexes to be examined.

Evaluation of rockfish abundance in untrawlable habitat: combining acoustic and complementary sampling tools

Rockfishes (Sebastes spp.) are an important component of North Pacific marine ecosystems and commercial fisheries. Because the rocky, high-relief substrate that rockfishes often inhabit is inaccessible to standard survey trawls, population abundance assessments for many rockfish species are difficult. As part of a large study to classify substrate and compare complementary sampling tools, we investigated the feasibility of using an acoustic survey in conjunction with a lowered stereo-video camera, a remotely operated vehicle, and a modified bottom trawl to estimate rockfish biomass in untrawlable habitat. The Snakehead Bank south of Kodiak Island, Alaska, was surveyed repeatedly over 4 days and nights. Dusky rockfish (S. variabilis), northern rockfish (S. polyspinis), and harlequin rockfish (S. variegatus) were the most abundant species observed on the bank. Backscatter attributed to rockfish were collected primarily near the seafloor at a mean height off the bottom of 1.5 m. Total rockfish backscatter and the height of backscatter off the bottom did not differ among survey passes or between night and day. Biomass estimates for the 41 square nautical-mile area surveyed on this small, predominantly untrawlable bank were 2350 metric tons (t) of dusky rockfish, 331 t of northern rockfish, and 137 t of harlequin rockfish. These biomass estimates are 5–60 times the density estimated for these rockfish species by a regularly conducted bottom trawl survey covering the bank and the surrounding shelf. This finding shows that bottom trawl surveys can underestimate the abundance of rockfishes in untrawlable areas and, therefore, may underestimate overall population abundance for these species.

Inferring Population Genetic Structure in Widely and Continuously Distributed Carnivores: The Stone Marten (Martes foina) as a Case Study

The stone marten is a widely distributed mustelid in the Palaearctic region that exhibits variable habitat preferences in different parts of its range. The species is a Holocene immigrant from southwest Asia which, according to fossil remains, followed the expansion of the Neolithic farming cultures into Europe and possibly colonized the Iberian Peninsula during the Early Neolithic (ca. 7,000 years BP). However, the population genetic structure and historical biogeography of this generalist carnivore remains essentially unknown. In this study we have combined mitochondrial DNA (mtDNA) sequencing (621 bp) and microsatellite genotyping (23 polymorphic markers) to infer the population genetic structure of the stone marten within the Iberian Peninsula. The mtDNA data revealed low haplotype and nucleotide diversities and a lack of phylogeographic structure, most likely due to a recent colonization of the Iberian Peninsula by a few mtDNA lineages during the Early Neolithic. The microsatellite data set was analysed with a) spatial and non-spatial Bayesian individual-based clustering (IBC) approaches (STRUCTURE, TESS, BAPS and GENELAND), and b) multivariate methods [discriminant analysis of principal components (DAPC) and spatial principal component analysis (sPCA)]. Additionally, because isolation by distance (IBD) is a common spatial genetic pattern in mobile and continuously distributed species and it may represent a challenge to the performance of the above methods, the microsatellite data set was tested for its presence. Overall, the genetic structure of the stone marten in the Iberian Peninsula was characterized by a NE-SW spatial pattern of IBD, and this may explain the observed disagreement between clustering solutions obtained by the different IBC methods. However, there was significant indication for contemporary genetic structuring, albeit weak, into at least three different subpopulations. The detected subdivision could be attributed to the influence of the rivers Ebro, Tagus and Guadiana, suggesting that main watercourses in the Iberian Peninsula may act as semi-permeable barriers to gene flow in stone martens. To our knowledge, this is the first phylogeographic and population genetic study of the species at a broad regional scale. We also wanted to make the case for the importance and benefits of using and comparing multiple different clustering and multivariate methods in spatial genetic analyses of mobile and continuously distributed species.

Potential use of offshore marine structures in rebuilding an overfished rockfish species, bocaccio (Sebastes paucispinis)

Although bocaccio (Sebastes paucispinis) was an economically important rockfish species along the west coast of North America, overfishing has reduced the stock to about 7.4% of its former unfished population. In 2003, using a manned research submersible, we conducted fish surveys around eight oil and gas platforms off southern California as part of an assessment of the potential value of these structures as fish habitat. From these surveys, we estimated that there was a minimum of 430,000 juvenile bocaccio at these eight structures. We determined this number to be about 20% of the average number of juvenile bocaccio that survive annually for the geographic range of the species. When these juveniles become adults, they will contribute about one percent (0.8%) of the additional amount of fish needed to rebuild the Pacific Coast population. By comparison, juvenile bocaccio recruitment to nearshore natural nursery grounds, as determined through regional scuba surveys, was low in the same year. This research demonstrates that a relatively small amount of artificial nursery habitat may be quite valuable in rebuilding an overfished species.

New Nuclear SNP Markers Unravel the Genetic Structure and Effective Population Size of Albacore Tuna (Thunnus alalunga)

In the present study we have investigated the population genetic structure of albacore (Thunnus alalunga, Bonnaterre 1788) and assessed the loss of genetic diversity, likely due to overfishing, of albacore population in the North Atlantic Ocean. For this purpose, 1,331 individuals from 26 worldwide locations were analyzed by genotyping 75 novel nuclear SNPs. Our results indicated the existence of four genetically homogeneous populations delimited within the Mediterranean Sea, the Atlantic Ocean, the Indian Ocean and the Pacific Ocean. Current definition of stocks allows the sustainable management of albacore since no stock includes more than one genetic entity. In addition, short-and long-term effective population sizes were estimated for the North Atlantic Ocean albacore population, and results showed no historical decline for this population. Therefore, the genetic diversity and, consequently, the adaptive potential of this population have not been significantly affected by overfishing.

Reprodução e parasitismo em Melanoides tuberculata (Müller, 1774) (Gastropoda, Thiaridae) da Vila do Abraão, Ilha Grande, Angra dos Reis, RJ

Melanoides tuberculata (Müller, 1774), molusco exótico límnico de origem afroasiática, foi registrado pela primeira vez na Vila do Abraão, Ilha Grande, Angra dos Reis, Rio de Janeiro, em 2005. Atua como primeiro hospedeiro intermediário de diversos trematódeos de importância médica. As populações são compostas majoritariamente por fêmeas partenogenéticas que possuem um marsúpio onde se desenvolvem os juvenis. Os objetivos foram verificar: a presença de machos; se existem flutuações na produção de ovos e juvenis ao longo do tempo; quando a maturidade sexual é atingida e, a existência de parasitos relacionando sua presença com o número de ovos e juvenis. Para a contagem de ovos e juvenis, foram utilizadas fêmeas coletadas bimestralmente de setembro/07 a outubro/10, separadas em quatro classes de tamanho, segundo o diâmetro da concha: Classe I: < 3mm; Classe II: 3 a 5,99mm; Classe III: 6 a 8,99mm; Classe IV: > 9mm. Separamos cinco fêmeas/classe, totalizando 20 fêmeas/coleta, exceto nas amostras de setembro/07 (16 exemplares), abril/09 (19 exemplares) e de abril/10 (13 exemplares), totalizando 348 fêmeas. Para observação dos parasitos, ovos e juvenis o teto da cavidade palial foi retirado e o marsúpio dissecado. Classificamos os juvenis em classes de acordo com o número de voltas: com menos de duas; com duas a quatro e com mais de quatro. Os dados foram analisados utilizando Excel e SYSTAT 12. Para a histologia da gônada e do marsúpio, utilizamos cinco exemplares coletados mensalmente de setembro/12 a fevereiro/13, de cada classe de tamanho, totalizando 20 espécimes/coleta, exceto em outubro/12, quando 16 espécimes foram usados, pois somente um espécime da Classe IV foi encontrado. Os espécimes foram fixados em formalina Millonig de Carson, descalcificados em EDTA, incluídos em parafina e corados em hematoxilina e eosina. Foram encontrados 16 machos. Quantificamos 24.694 ovos e 31.474 juvenis, com as seguintes médias: Classe I: 0 ovos e 0,31 juvenis; Classe II: 24,19 ovos e 47,56 juvenis; Classe III: 114,84 ovos e 155,78 juvenis; Classe IV: 146,76 ovos e 158,41 juvenis. O teste de Kruskal-Wallis mostrou que existe variação significativa no número de ovos e juvenis ao longo do ano (p < 0,01 para ambos) e entre o número de ovos e juvenis entre as diferentes classes de tamanho de concha (p <0,01 para ambos). Foram contabilizados 27.877 juvenis com menos de duas voltas, 3.251 juvenis com duas a quatro voltas e 346 juvenis com mais de quatro voltas. Dentre 348 fêmeas, 111 estavam parasitadas (32% do total) por Centrocestus formosanus (Nishigori, 1924). O Teste de Mann-Whitney, levando em consideração todas as fêmeas, demonstrou que fêmeas parasitadas apresentaram menor número de ovos e juvenis que as não parasitadas ( p<0,01). Excluindo as fêmeas da Classe 1, o resultado do teste foi o mesmo (p< 0,01). Concluímos que: a população de M. tuberculata da Vila do Abraão não é formada somente por fêmeas; as fêmeas se reproduzem o ano todo, pois foram encontrados ovos e juvenis em todas as coletas; que quanto maior a fêmea há mais ovos e, em média, há mais juvenis no marsúpio; que a maturidade sexual é alcançada com aproximadamente 3 mm de diâmetro de concha, devido a presença de ovócitos vitelogênicos tardios e, que o parasitismo afeta negativamente M. tuberculata, reduzindo o número de ovos e juvenis formados

A comparison of two fishery-independent survey programs used to define the population structure of American lobster (Homarus americanus) in the Gulf of Maine

The population structure and abundance of the American lobster (Homarus americanus) stock in the Gulf of Maine are defined by data derived from a fishery-independent trawl survey program conducted by the National Marine Fisheries Service (NMFS). Few sampling stations in the survey area are located inshore, in particular along coastal Maine. According to statistics, however, more than two thirds of the lobster landings come from inshore waters within three miles off the coast of Maine. In order to include an inshore survey program, complementary to the NMFS survey, the Maine Department of Marine Resources (DMR) initialized an inshore survey program in 2000. The survey was modeled on the NMFS survey program, making these two survey programs comparable. Using data from both survey programs, we evaluated the population structure of the American lobster in the Gulf of Maine. Our findings indicate that lobsters in the Gulf of Maine tend to have a size-dependent inshore-off-shore distribution; smaller lobsters are more likely to stay inshore and larger lobsters are more likely to stay offshore. The DMR inshore and NMFS survey programs focused on different areas in the Gulf of Maine and likely targeted different segments of the stock. We suggest that data from both survey programs be used to assess the lobster stock and to describe the dynamics of the stock in the Gulf of Maine.

The effect of predation (current and historical) by humpback whales (Megaptera novaeangliae) on fish abundance near Kodiak Island, Alaska

Humpback whales (Megaptera novaeangliae) are significant marine consumers. To examine the potential effect of predation by humpback whales, consumption (kg of prey daily) and prey removal (kg of prey annually) were modeled for a current and historic feeding aggregation of humpback whales off northeastern Kodiak Island, Alaska. A current prey biomass removal rate was modeled by using an estimate of the 2002 humpback whale abundance. A historic rate of removal was modeled from a prewhaling abundance estimate (population size prior to 1926). Two provisional humpback whale diets were simulated in order to model consumption rate. One diet was based on the stomach contents of whales that were commercially harvested from Port Hobron whaling station in Kodiak, Alaska, between 1926 and 1937, and the second diet, based on local prey availability as determined by fish surveys conducted within the study area, was used to model consumption rate by the historic population. The latter diet was also used to model consumption by the current population and to project a consumption rate if the current population were to grow to reach the historic population size. Models of these simulated diets showed that the current population likely removes nearly 8.83

Population structure and variance effective size of red snapper (Lutjanus campechanus) in the northern Gulf of Mexico*

We assayed allelic variation at 19 nuclear-encoded microsatellites among 1622 Gulf red snapper (Lutjanus campechanus) sampled from the 1995 and 1997 cohorts at each of three offshore localities in the northern Gulf of Mexico (Gulf). Localities represented western, central, and eastern subregions within the northern Gulf. Number of alleles per microsatellite per sample ranged from four to 23, and gene diversity ranged from 0.170 to 0.917. Tests of conformity to Hardy-Weinberg equilibrium expectations and of genotypic equilibrium between pairs of micro-satellites were generally nonsignificant following Bonferroni correction. Significant genic or genotypic heterogeneity (or both) among samples was detected at four microsatellites and over all microsatellites. Levels of divergence among samples were low (FST ≤0.001). Pairwise exact tests revealed that six of seven “significant” comparisons involved temporal rather than spatial heterogeneity. Contemporaneous or variance effective size (NeV) was estimated from the temporal variance in allele frequencies by using a maximum-likelihood method. Estimates of NeV ranged between 1098 and >75,000 and differed significantly among localities; the NeV estimate for the sample from the northcentral Gulf was >60 times as large as the estimates for the other two localities. The differences in variance effective size could ref lect differences in number of individuals successfully reproducing, differences in patterns and intensity of immigration, or both, and are consistent with the hypothesis, supported by life-history data, that different “demographic stocks” of red snapper are found in the northern Gulf. Estimates of NeV for red snapper in the northern Gulf were at least three orders of magnitude lower than current estimates of census size (N). The ratio of effective to census size (Ne/N) is far below that expected in an ideal population and may reflect high variance in individual reproductive success, high temporal and spatial variance in productivity among subregions or a combination of the two.

Comportamento sexual e uso de álcool e drogas entre homens que fazem sexo com homens no Ceará: tendências e práticas de risco para DST/AIDS

No Brasil, o s casos de AIDS entre homens que fazem sexo com homens (HSH) predominaram durante um longo período. A partir da década de 90, observa-se um declínio nesta categoria com o aumento de casos entre heterossexuais. Na região Nordeste, entretanto, os casos de AIDS entre HSH representam, ainda, cerca de 50% do total dos casos registrados em anos recentes. Nosso objetivo foi estudar o comportamento sexual e o padrão de consumo de drogas e álcool entre HSH no Ceará, enfatizando as tendências recentes e suas relações com práticas sexuais de risco para DTS/AIDS. Foram realizados quatro estudos seccionais em 1995, 1998, 2002 e 2005 no Ceará, nordeste do Brasil. A população do estudo foi composta por homens que fazem sexo com homens (HSH), com 14 anos ou mais , que referiram prática sexual anal ou oral com homens nos últimos 12 meses. A seleção dos participantes utilizou técnicas do tipo Snow Ball (1995, 1998, 2002); Time Space Sampling (2002) e Respondent Driven Sampling (2005). O primeiro artigo enfoca as tendências do comportamento sexual em Fortaleza ao longo destes quatro períodos e o segundo os preditores do consumo de álcool e drogas nos municípios de Fortaleza (n=401), Sobral (n=100) e a região do Cariri (n=100) em 2002. Análise se basearam nas comparações entre proporções, utilizando o teste do de Pearson e intervalos de 95% de confiança (IC95%) e análise de regressão logística multivariada para avaliação dos fatores associados ao consumo de álcool e drogas, utilizando-se como medida de associação a razão de chances (odds ratio OR) e seus respectivos intervalos de 95% de confiança. Resultados Práticas sexuais: Elevado percentual da população estudada referiu práticas sexuais de risco em 1995 (49,9%), decrescendo significativamente em 1998 (32,6%), tornando a crescer em 2002 (54,6%) e apresentando os menores percentuais em 2005 (31,4%). Este padrão não apresentou grandes variações por idade, mas em relação à escolaridade observou-se que os indivíduos com escolaridade mais elevada aumentaram as práticas de risco entre 1998 (28,6%) e 2002 (46,5%) decrescendo no último período (21,0%) enquanto aqueles com baixa ou média escolaridade só mostraram uma queda significativa no comportamento de risco entre 2002 (82,1% - baixa; 67,7% - média) e 2005 (29,1% - baixa; 34,3 média). A prática sexual anal com preservativo cresceu no decorrer dos anos variando de 43,3% a 53,7% entre a primeira e a última onda ( de tendência p<0.001). A relação anal sem preservativo foi uma prática com alto percentual na maioria dos anos. De 2002 a 2005, houve uma diminuição significativa (de alto percentual na maioria dos anos. De 2002 a 2005, houve uma diminuição significativa (de 57,7% para 26,3%) das relações fixas monogâmicas. Consumo de álcool e drogas: No estudo, 63% dos HSH participantes foram classificados como bebedores que se embriagam. Observou-se que o consumo crescente de álcool leva a um aumento do uso concomitante de outras drogas, sejam lícitas ou ilícitas. Foram variáveis preditoras de beber se embriagando: ter de 21 a 30 anos (OR: 1,5; IC 95%: 1,1-2,9); ter mais que 30 anos (OR: 1,6: IC95%: 1,2-2,3); ser solteiro/separado/divorciado (OR:3,0%; IC95%: 1,7-5,3); ser da raça negra (OR: 2,0 IC95%: 1,7-2,01); ser da raça parda (OR: 1,8 IC95%: 1,3-2,6); receber dinheiro por sexo (OR:2,0 IC95%: 1,8-2,9). As práticas sexuais dos SHS em Fortaleza apresentaram variações significativas ao longo doa anos estudados, semelhantemente a outros estudos internacionais. Vários fatores poderiam ser responsáveis por explicar o comportamento da curva observada em Fortaleza, seja no âmbito local, nacional ou internacional. Entre os fatores que podem explicar alterações observadas estariam: 1) redução nos recursos destinados à prevenção da AIDS no país devido a retirada de alguns organismos de cooperação internacional que se voltaram para outros países, como na África Leste Europeu, levando o Brasil a priorizar segmentos populacionais com maior vulnerabilidade; 2) grande impacto na prevenção das DST /AIDS na comunidade de homo/bissexuais masculinos, especialmente nos anos de 1998 a 2002; 3) o avanço no tratamento, surgimento de novas drogas, melhora da qualidade de vida e aumento da sobrevida, contribuindo para a construção da falsa ideia de segurança na população. Neste estudo a escolaridade mostrou-se um fator importante associado ao envolvimento em práticas sexuais não seguras. Os indivíduos com mais baixa escolaridade, no período de 1995 a 2002, se envolveram em maior risco, aparentando não terem sido atingidos pelas campanhas que possam ter ocorrido, principalmente no período de 1995 a 1998. A maior escolaridade apresenta-se como fator de proteção em todo o período estudado, provavelmente pelo maior acesso à informação. Finalmente, pode-se observar no ano de 2002 um elevado percentual de homens que consomem cinco ou mais doses em um dia típico e associam outras drogas ao consumo do álcool. Tal comportamento, dentro da população HSH, embora não seja caracterizado como dependência química, é alterado de maneira significativa pelo efeito etílico, levando à outras práticas de risco. Também se observou em nosso estudo que o consumo crescente de álcool leva a um aumento do uso de outras drogas, atuando para a adoção de comportamentos de risco. Existem evidências que suportam relação entre uso de outras drogas e a prática sexual de risco. Os indivíduos que referiram receber dinheiro em troca de sexo foram mais frequentemente classificados como bebedores que se embriagam. Os achados deste estudo mostram a importância da realização de uma vigilância comportamental contínua em relação ao HIV favorecendo o entendimento da dinâmica da epidemia junto das DST/AIDS nesta população vulnerável, assim como a importância que o álcool assume como problema de saúde pública neta população específica e a necessidade de se direcionar medidas voltadas para a sua prevenção.

Population parameters of small pelagic fishes caught off Tawi-Tawi, Philippines

Growth and mortality parameters, exploitation rates and annual recruitment patterns were estimated from monthly length-frequency samples for Sardinella longiceps, S. fimbriata, S. Albella, Decapterus macrosoma, Dipterygonatus balteatus, Rastrelliger faughni and Encrasicolina heteroloba. These results provide the first sets of stock parameter estimates for these species off Tawi-Tawi, Philippines. The growth parameters derived were found comparable with previous estimates available for the same species from other localities. Recruitment was noted to be year-round and bimodal. Estimates of fishing mortality and exploitation rate were found to be presently above appropriate levels.

Population parameters of Penaeus californiensis in the Gulf of Guayaquil, Ecuador

The growth, mortality, and recruitment pattern of Penaeus californiensis were investigated using tail length (TL)-frequency data obtained from the Gulf of Guayaquil shrimp population. Computer-based methods of tail-frequency analysis Compleat ELEFAN software were used. Results obtained gave relatively high growth and mortality estimates for both males and females. The recruitment pattern indicated two pulses annually, one significantly larger than the other.