Detection of protection benefits for predatory fishes depends on census methodology

Marine protected areas (MPAs) are used as fisheries management and conservation tools. Well-enforced no-take zones allow the rebuilding of natural populations of exploited species; however, there is still controversy on the role of buffer zones. The effectiveness of MPAs could be underestimated, as fish population assessments depend largely on traditional methodologies that have difficulties in detecting predatory fish because of their low abundances, their patchy distribution, and their reaction to the presence of divers. The performance of different census methods was compared in assessing the protection benefits for large predatory fishes under different protection levels (i.e. no-take and buffer zones) in five Mediterranean MPAs. Specifically, conventional strip transects (CSTs, 50 × 5 m2) and tracked roaming transects combined with distance sampling (TRT + DS, variable lengths) were compared, including a series of TRT-derived estimators with variable transect lengths and fixed widths of 20, 10, and 6 m (TRT20, TRT10, and TRT6, respectively). Additionally, the effectiveness of the MPAs studied and protection levels for conserving large predatory species was evaluated. Transects covering larger areas (i.e. TRT + DS and TRT20) allowed the detection of a greater number of species and yielded more accurate estimates of density and biomass than transects of narrower fixed widths, particularly the CSTs, which were associated with the lowest richness detection capability, accuracy, and precision. On average, both no-take zones and buffer zones appeared effective for the conservation of predatory fishes, indicating that multiple protection areas were ecologically effective. Differences between MPAs were also observed, however, probably arising from both local environmental and management factors. We suggest the implementation of methodologies with larger transects for the study of large predatory fish, combined with CSTs for the rest of the fish community, in order to avoid biases in predatory population assessments, which are key indicators of MPA effectiveness

Nycthemeral and Monthly Occupation of the Fish Assemblage on a Sheltered Beach of Baía Norte, Florianópolis, Santa Catarina State, Brazil

Interpreting fish community records is challenging for several reasons, including the lack of past ichthyofauna data, the cyclical temporal variations in the community, and the methodology employed, which usually underestimates fish assemblages. The objective of this study was to describe short-scale and meso-scale (nycthemeral period and months, respectively) temporal variations in the ichthyofauna composition and structure of a sheltered beach of Baía Norte (Florianópolis, Santa Catarina state, Brazil), using a capéchade net. Samples were collected monthly for a period of 48 hours. During the period from December 2010 to November 2011, a total of 19,302 individuals belonging to 89 species and 39 families were captured. The number of individuals that were sampled during the day and/or night was dependent on the sampling month. On average, the daytime assemblage was more abundant and different in structure and composition than the nighttime assemblage. Of the eight species that had the highest Index of Relative Importance (%IRI), five had higher variations (ANOVA F) between the day and night than between the months. This finding reinforced the need for sampling during both the day and night. The capéchade net effectively captured demersal and pelagic individuals in a broad range of sizes

A review of methods to assess connectivity and dispersal between fish populations in the Mediterranean Sea

Fish populations are linked to each other via dispersal of individuals as eggs, larvae, juveniles or adults. The understanding of this process, known as connectivity, has a pivotal role for the management of overexploited fish stocks and the development of accurate conservation strategies. Knowledge on connectivity and fish movements is considered fundamental toward the correct design of marine protected area (MPA) networks for the achievement of the benefits of protection. Connectivity patterns are still largely unknown worldwide. A general lack of knowledge is particularly evident for the Mediterranean Sea where few studies dealing with this topic have been carried out and some methods, currently available for assessing connectivity, have not been used yet. In this review we present the methods used for studying connectivity patterns and fish movements at different life history stages and the main results achieved until now in the Mediterranean Sea. We encompass the pros and cons of each method, and conclude with future perspectives on the use of these methodologies in the Mediterranean context. © 2013 © 2013 Taylor & Francis

Recovery of grouper assemblages indicates effectiveness of a marine protected area in Southern Brazil

Top predators have a strong influence on the structure and dynamics of marine ecosystems. These organisms have been largely used as indicators of the effectiveness of marine protected areas (MPAs). In Brazil, the impact of fisheries on reef species, such as groupers and sea basses, and the importance of local marine reserves in the maintenance of these fish communities are still poorly understood. Here we assessed the assemblage of groupers and sea basses (Epinephelidae and Serranidae) inside and outside the Arvoredo Marine Reserve (AR), a MPA in Santa Catarina State, southern Brazil. Density and biomass of 13 fish species (7 Epinephelidae and 6 Serranidae) were recorded. The most abundant groupers were Epinephelus marginatus and Mycteroperca acutirostris, while Serranus flaviventris and S. balwini were the most abundant sea basses. Grouper biomass was significantly higher inside the reserve, indicating the effectiveness of this MPA for target and threatened species, such as E. marginatus. In contrast, biomass of sea basses was higher outside the MPA, as a possible result of prey release effect. Despite the higher biomass of groupers inside AR, spearfishing records from the 1960s indicate that there is still a long way to a full recovery of the biomass of top predators, especially groupers and sharks. Thus, a more effective enforcement and longer-term protection are necessary to restore fish stocks and ecosystem health in these reefs.9 page(s

Diel and tidal variation in surf zone fish assemblages of a sheltered beach in southern Brazil Variación diaria y mareal de ensambles de peces en la zona de surf de una playa protegida en el sur de Brasil

Diel and tidal variations of fish assemblages were assessed at Pontal beach, southern Brazil, using a seine net. Species richness was greater at night, whereas fish number, weight, and richness (cornmunity indicators) were all influenced by the tidal state. Samples from rising tides were more representative, probably due to onshore fish movements for feeding purposes. However, lower catches were associated with high tides, mainly through net avoidance, indicating that sampling in these conditions is not highly informative. Clupeoids exhibited greater variation in a 24 h period, and the night occurrence of A. tricolor and daylight shoaling of Harengula clupeola, Anchoa parva and Sardinella brasiliensis suggested distinct strategies for avoiding daylight predators. In some species, this behaviour may have been induced by the bottom morphology and tidal state, facilitating nearshore grouping. In addition to being caught at night, the occurrences of Menticirrhus littoralis, Pomadasys corvinaefórmis, Umbrina coroides and Hyporhamphus unifasciatus indicated a spatial niche partition according to tidal state. Although not evaluated properly, temporal fluctuations could reflect species recruitment patterns. Seasonal fluctuations have to be considered when analysing short-term changes in the cornmunity as such fluctuations are synchronized with the natural history of the species, making it difficult to interpret short-term variations in isolation.Se utilizó una red de arrastre para evaluar la variación diaria y mareal del ensamble de peces en la playa de Pontal, sur de Brasil. Se encontró la mayor riqueza de especies durante la noche mientras que la abundancia, peso y riqueza (indicadores de la comunidad) fueron influenciados por la marea. Las muestras de marea creciente fueron las más representativas debido probablemente a los movimientos costeros con fines alimentarios; sin embargo, las menores capturas estuvieron asociadas a pleamares debido a la evasion a la red, indicando que los muéstreos en estas condiciones son poco informativos. Los clupeidos fueron los peces que más variaron durante un periodo de 24 h; la ocurrencia nocturna de A. tricolor y el agrupamiento matutino de Harengula clupeola, Anchoa parva and Sardinella brasiliensis sugieren distintas estrategias en la evasion de los depredadores diurnos. La morfología del fondo asociada con la marea, puede haber influenciado el comportamiento de algunas especies, facilitándoles el agrupamiento costero. Además de haber sido capturadas por la noche, la ocurrencia de Menticirrhus littoralis, Pomadasys corvinaefórmis, Umbrina coroides and Hyporhamphus unifasciatus indicó la repartición espacial del nicho según el estado de la marea. Aunque no evaluadas correctamente, las fluctuaciones temporales pueden reflejar los patrones específicos de reclutamiento; la estacionalidad debe ser incluida cuando se estudian desplazamientos de corto plazo en la comunidad debido a su sincronización con la historia natural de las especies, haciendo que las variaciones de corto plazo sean difíciles de interpretar por sí solas

Diel and tidal variation in surf zone fish assemblages of a sheltered beach in southern Brazil

Diel and tidal variations of fish assemblages were assessed at Pontal beach, southern Brazil, using a seine net. Species richness was greater at night, whereas fish number, weight, and richness (cornmunity indicators) were all influenced by the tidal state. Samples from rising tides were more representative, probably due to onshore fish movements for feeding purposes. However, lower catches were associated with high tides, mainly through net avoidance, indicating that sampling in these conditions is not highly informative. Clupeoids exhibited greater variation in a 24 h period, and the night occurrence of A. tricolor and daylight shoaling of Harengula clupeola, Anchoa parva and Sardinella brasiliensis suggested distinct strategies for avoiding daylight predators. In some species, this behaviour may have been induced by the bottom morphology and tidal state, facilitating nearshore grouping. In addition to being caught at night, the occurrences of Menticirrhus littoralis, Pomadasys corvinaefórmis, Umbrina coroides and Hyporhamphus unifasciatus indicated a spatial niche partition according to tidal state. Although not evaluated properly, temporal fluctuations could reflect species recruitment patterns. Seasonal fluctuations have to be considered when analysing short-term changes in the cornmunity as such fluctuations are synchronized with the natural history of the species, making it difficult to interpret short-term variations in isolation

The role of institutional quality in the international trade of a Latin American country: evidence from Colombian export performance

Abstract This paper analyses the relevance of Colombian institutional quality in recent years in terms of the performance of its exports within a framework of trade openness. Based on the trade gravity model, we examine the effect of governance on the evolution of Colombian exports through an econometric approach that identifies, on the one hand, the influence of institutional quality, and on the other hand, the influence of the institutional distance between Colombia and its trading partners. We use a panel data set for 2005–2018, through which the export flows from Colombia to 136 of its trading partners are considered. The findings indicate that Colombian institutional quality and the institutional distance between the country and its partners are statistically significant and affect its foreign sales. Similarly, there is a prominent influence of regulatory quality and the rule of law variables in the performance of Colombian exports in relation to other variables included in the model. We conclude that the Colombian government must improve its institutional quality considerably as a fundamental step towards boosting its overseas sales, not least because the country’s institutional distance from the world average is notable, which also affects its exports