scholarly journals Comprehensive Spatial Distribution of Tropical Fish Assemblages from Multifrequency Acoustics and Video Fulfils the Island Mass Effect Framework

2021 ◽  
Author(s):  
Julie Salvetat ◽  
Nicolas Bez ◽  
Jeremie Habasque ◽  
Anne Lebourges-Dhaussy ◽  
Cristiano Lopez ◽  
...  
Keyword(s):  
Spatial Distribution ◽  
Fish Assemblages ◽  
Mass Effect ◽  
Fish Distribution ◽  
Tropical Fish ◽  
Small Scale ◽  
Biomass Estimation ◽  
Small Scale Fisheries ◽  
Video Observations ◽  
Fernando De Noronha

Abstract Tropical marine ecosystems are highly biodiverse and provide resources for small-scale fisheries and tourism. However, precise information on fish spatial distribution is lacking, which limits our ability to reconcile exploitation and conservation. We combined acoustics to video observations to provide a comprehensive description of fish distribution in a typical tropical environment, the Fernando de Noronha Archipelago (FNA) off Northeast Brazil. We identified and classified all acoustic echoes into ten fish assemblage and two triggerfish species. This opened up the possibility to relate the spatial different spatial patterns to a series of environmental factors and the level of protection. We provide the first biomass estimation of the black triggerfish Melichthys niger, a key tropical player. By comparing the effects of euphotic and mesophotic reefs we show that more than the depth, the most important feature is the topography with the shelf break as the most important hotspot. We also complete the portrait of the island mass effect revealing a clear asymmetry. While primary productivity is higher downstream, fish concentrate upstream. The comprehensive fish distribution provided by our approach is directly usable to implement scientific-grounded Marine Spatial Planning.

scholarly journals Experimental evaluation of influence of FADs on community structure and fisheries in coastal Kenya

2018 ◽  
Vol 31 ◽  
pp. 6 ◽  
Author(s):  
Emmanuel K. Mbaru ◽  
Dorcas Sigana ◽  
Renison K. Ruwa ◽  
Elizabeth M. Mueni ◽  
Collins K. Ndoro ◽  
...  
Keyword(s):  
Fish Assemblages ◽  
Small Scale ◽  
Catch Per Unit Effort ◽  
Fish Stocks ◽  
Coastal Fisheries ◽  
Small Scale Fisheries ◽  
Open Sea ◽  
Catch Composition ◽  
Structural Indices ◽  
Fish Aggregating Devices

Fish aggregating devices (FADs) have been widely used by commercial fisheries to increase the catchability of pelagic stocks in the open sea. FADs have the potential to enhance nearshore small-scale fisheries where stocks are often overfished. This study examined changes in catch composition, abundance, catch and effort, and aspects of diversity in Kenya's nearshore coastal fisheries after deployment of anchored fish aggregating devices (AFADs). The study combined both fishery independent and dependent methods in assessing changes in fish assemblages post-deployment. Results showed orders of magnitude increase in length, weight, commercial value, and catch per unit effort (CPUE) of landed catch after deployment of FADs suggesting that FADs had a positive effect on the local fishery. Species richness at FAD sites increased post-deployment (n = 281) compared to pre-deployment values (n = 223). Simultaneous use of several complementary structural indices may be required in order to accurately describe and monitor fish assemblages around the FADs. The findings suggest that AFADs are capable of creating both short and long-term impacts on livelihoods, with the potential to deflect pressure on the overfished nearshore fish stocks. However, more research will be needed on redistribution of fish around FADs, design and placement configuration, and site selection amongst others.

scholarly journals Supporting Spatial Management of Data-Poor, Small-Scale Fisheries With a Bayesian Approach

2021 ◽  
Vol 8 ◽  
Author(s):  
Jennifer Rehren ◽  
Maria Grazia Pennino ◽  
Marta Coll ◽  
Narriman Jiddawi ◽  
Christopher Muhando
Keyword(s):  
Spatial Distribution ◽  
Marine Conservation ◽  
Environmental Drivers ◽  
Small Scale ◽  
Target Species ◽  
Short Term ◽  
Conservation Areas ◽  
Bayesian Hierarchical ◽  
Small Scale Fisheries ◽  
Spatial Management

Marine conservation areas are an important tool for the sustainable management of multispecies, small-scale fisheries. Effective spatial management requires a proper understanding of the spatial distribution of target species and the identification of its environmental drivers. Small-scale fisheries, however, often face scarcity and low-quality of data. In these situations, approaches for the prioritization of conservation areas need to deal with scattered, biased, and short-term information and ideally should quantify data- and model-specific uncertainties for a better understanding of the risks related to management interventions. We used a Bayesian hierarchical species distribution modeling approach on annual landing data of the heavily exploited, small-scale, and data-poor fishery of Chwaka Bay (Zanzibar) in the Western Indian Ocean to understand the distribution of the key target species and identify potential areas for conservation. Few commonalities were found in the set of important habitat and environmental drivers among species, but temperature, depth, and seagrass cover affected the spatial distribution of three of the six analyzed species. A comparison of our results with information from ecological studies suggests that our approach predicts the distribution of the analyzed species reasonably well. Furthermore, the two main common areas of high relative abundance identified in our study have been previously suggested by the local fisher as important areas for spatial conservation. By using short-term, catch per unit of effort data in a Bayesian hierarchical framework, we quantify the associated uncertainties while accounting for spatial dependencies. More importantly, the use of accessible and interpretable tools, such as the here created spatial maps, can frame a better understanding of spatio-temporal management for local fishers. Our approach, thus, supports the operability of spatial management in small-scale fisheries suffering from a general lack of long-term fisheries information and fisheries independent data.

scholarly journals Effect of temporal and spatial resolution on identification of fishing activities in small-scale fisheries using pots and traps

2019 ◽  
Vol 76 (6) ◽  
pp. 1601-1609 ◽  
Author(s):  
Tania Mendo ◽  
Sophie Smout ◽  
Tommaso Russo ◽  
Lorenzo D’Andrea ◽  
Mark James
Keyword(s):  
Spatial Distribution ◽  
Spatial Resolution ◽  
Large Scale ◽  
Low Cost ◽  
Grid Cell ◽  
Analysis Data ◽  
Satellite System ◽  
Small Scale ◽  
Fishing Activity ◽  
Small Scale Fisheries

Abstract Analysis of data from vessel monitoring systems and automated identification systems in large-scale fisheries is used to describe the spatial distribution of effort, impact on habitats, and location of fishing grounds. To identify when and where fishing activities occur, analysis needs to take account of different fishing practices in different fleets. Small-scale fisheries (SSFs) vessels have generally been exempted from positional reporting requirements, but recent developments of compact low-cost systems offer the potential to monitor them effectively. To characterize the spatial distribution of fishing activities in SSFs, positions should be collected with sufficient frequency to allow detection of different fishing behaviours, while minimizing demands for data transmission, storage, and analysis. This study sought to suggest optimal rates of data collection to characterize fishing activities at appropriate spatial resolution. In a SSF case study, on-board observers collected Global Navigation Satellite System (GNSS) position and fishing activity every second during each trip. In analysis, data were re-sampled to lower temporal resolutions to evaluate the effect on the identification of number of hauls and area fished. The effect of estimation at different spatial resolutions was also explored. Consistent results were found for polling intervals <60 s in small vessels and <120 in medium and large vessels. Grid cell size of 100 × 100 m resulted in best estimations of area fished. Remote collection and analysis of GNSS or equivalent data at low cost and sufficient resolution to infer small-scale fisheries activities. This has significant implications globally for sustainable management of these fisheries, many of which are currently unregulated.

Controls on fish distribution and abundance in temporary wetlands

2002 ◽  
Vol 59 (9) ◽  
pp. 1441-1450 ◽  
Author(s):  
Matthew J Baber ◽  
Daniel L Childers ◽  
Kimberly J Babbitt ◽  
David H Anderson
Keyword(s):  
Large Scale ◽  
Fish Assemblages ◽  
Fish Distribution ◽  
Temporary Ponds ◽  
Small Scale ◽  
Cattle Ranching ◽  
Temporary Wetlands ◽  
Local Characteristics ◽  
Landscape Processes ◽  
Colonization Dynamics

Our main goal was to determine if fish distribution and adundance in temporary wetlands were shaped primarily by large-scale (landscape) or small-scale (local) characteristics and to investigate the influence of cattle ranching on fish assemblages. A total of 24 temporary ponds were selected at the Kissimmee Prairie Sanctuary and the Mac Arthur Agro-Ecology Research Center. Each wetland was sampled for fish using throw traps and dip nets during 1999. Landscape processes (connectivity to permanent water bodies) predominately influenced fish assemblages, although local processes (depth–hydroperiod) were also important. Furthermore, no colonizing species went locally extinct before wetlands began to dry. Our findings suggest that large-scale processes that influence colonization dynamics are of more importance than small-scale processes that influence extinction dynamics. Finally, hydrological changes (ditching) associated with agriculture (cattle ranching) have adversely affected temporary wetland fish assemblages by reducing wetland hydroperiods and connectivity.

scholarly journals Impacts of small-scale fisheries on mangrove fish assemblages

2018 ◽  
Vol 76 (1) ◽  
pp. 153-164 ◽  
Author(s):  
José Amorim Reis-Filho ◽  
Euan S Harvey ◽  
Tommaso Giarrizzo
Keyword(s):  
Species Richness ◽  
Fishery Management ◽  
Management Practices ◽  
Fish Assemblages ◽  
Small Scale ◽  
Fishing Pressure ◽  
Community Size ◽  
Small Scale Fisheries ◽  
Fishing Impacts ◽  
The Impact

Abstract The data requirements and resources needed to develop effective indicators of fishing impacts on target stocks may often be great, especially for mangrove fisheries where, for example, tidal cycles sequentially flood and drain the habitat as a result of natural processes. Here, we used underwater video systems to evaluate the impact of small-scale fisheries on mangrove fish assemblages at four levels of fishing pressure (low, medium, high, and no pressure). The lowest values of species richness and abundance were recorded in the areas fished most intensively. Conversely, the highest species richness and the occurrence of larger-bodied fish were recorded in areas of reduced fishing activity, which was surprisingly similar to the “no fishing” areas. The slopes of the community size spectra steepened in response to exploitation, while the relative abundance of medium-sized fish (16–25 cm) declined. Fishing for local or regional markets, rather than subsistence, also led to a decrease in the abundance of larger fish (>41 cm). The marked response of population parameters to fishing pressure reflected the impact of unregulated small-scale fisheries on areas of mangroves. Fishery management practices that ignore contemporary changes in these environments are likely to overestimate long-term yields, leading to overfishing. Thus, size-based approaches to evaluating fishing pressure were suitable for detecting negative responses from the mangrove fish assemblages. A next step will be to integrate size- and species-based ecological approaches that provide mechanisms to address pronounced decreases in specific species as a more profitable indicator of fishing impacts on mangrove fish assemblages. This approach will allow the development of effective conservation and management strategies.

scholarly journals Seagrass Structural Traits Drive Fish Assemblages in Small-Scale Fisheries

2021 ◽  
Vol 8 ◽  
Author(s):  
Benjamin L. Jones ◽  
Lina M. Nordlund ◽  
Richard K. F. Unsworth ◽  
Narriman S. Jiddawi ◽  
Johan S. Eklöf
Keyword(s):  
Species Richness ◽  
Species Diversity ◽  
Fish Assemblages ◽  
Human Impacts ◽  
Structural Complexity ◽  
Tropical Fish ◽  
Small Scale ◽  
Seagrass Species ◽  
Seagrass Meadows ◽  
Seagrass Cover

Seagrasses – a group of foundation species in coastal ecosystems – provide key habitat for diverse and abundant faunal assemblages and support numerous ecosystem functions and services. However, whether the habitat role of seagrasses is influenced by seagrass diversity, by dominant species or both, remains unclear. To that end, we sought to investigate the specific seagrass characteristics (e.g., species diversity, seagrass traits) that influence tropical fish assemblages, and place this in the context of small-scale fishery use. We surveyed seagrass variables at 55 plots, nested within 12 sites around Zanzibar (Tanzania) in the Western Indian Ocean, and used Baited Remote Underwater Video (BRUV) systems to assess fish assemblages across plots. Using linear mixed models, we reveal that seagrass structural complexity and depth were the best predictors of fish abundance, with higher abundance occurring in deeper meadows or meadows with high canopy, leaf length and number of leaves per shoot. Moreover, an interaction between seagrass cover and land-use was the best predictor of fish species richness, where sites closer to human impacts were less affected by cover than sites with lower human impact. Overall, models with seagrass species richness or functional diversity as predictors poorly explained fish assemblages. Fish taxa that were important for small-scale fishery sectors (e.g., emperors, snappers, rabbitfish, and parrotfish) were primarily driven by seagrass structural complexity. Our results provide a unique analysis of the relationship between seagrass habitat and its associated fish assemblages in that we show that seagrass species diversity had little effect on seagrass fish assemblages, which instead appear driven by specific seagrass traits and seagrass cover. If conserving high value species that support adjacent fisheries is the priority for protecting seagrass meadows, then seagrass areas should be chosen with high cover and structural complexity that are in deeper waters. Any conservation measures also need to balance the needs of fishers that use the resources supported by seagrasses.

scholarly journals Species composition and spatial distribution of a stream fish assemblage in the east coast of Brazil: comparison of two field study methodologies

2001 ◽  
Vol 61 (3) ◽  
pp. 377-388 ◽  
Author(s):  
V. S. UIEDA ◽  
W. UIEDA
Keyword(s):  
Spatial Distribution ◽  
Species Composition ◽  
Fish Assemblage ◽  
East Coast ◽  
Fish Assemblages ◽  
High Water ◽  
Flow Speed ◽  
The Other ◽  
Tropical Fish ◽  
Running Waters

The species composition and spatial distribution of a fish assemblage were studied in three reaches of a river in the east coast of Brazil: a section of rapids (upper), another of water flowing on plain terrain (lowland) and the other of a mangrove environment. Two methods were employed with the purpose of estimating their effectiveness in naturalistic studies of tropical fish assemblages. One method consisted of underwater observations and the other was characterized by catches using gears such as fish traps, sieves and fishing rods. Both methods showed that their effectiveness is dependent upon the characteristics of the environment and the biology of the species. In areas of high water transparency and flow speed, rocky substrate and no submerged marginal vegetation (upper reach), the employment of the traditional gears was quite inefficient, despite the excellent conditions for underwater observations. In areas of clear water and high flow speed with abundant submerged marginal vegetation (lowland and mangrove), the gears were rather efficient yielding excellent results when coupled with direct observation methods. Since the abiotic characteristics of a stream change longitudinally, it is appropriate to employ different methods in the study of the ichthyofauna composition and distribution in order to reduce the constraints imposed by sampling methods in running waters.

scholarly journals Spatio-Temporal Determination of Small-Scale Vessels’ Fishing Grounds Using a Vessel Monitoring System in the Southeastern Gulf of Mexico

2021 ◽  
Vol 8 ◽  
Author(s):  
Edgar Torres-Irineo ◽  
Silvia Salas ◽  
Jorge Iván Euán-Ávila ◽  
Leopoldo E. Palomo ◽  
Daniel R. Quijano Quiñones ◽  
...  
Keyword(s):  
Spatial Distribution ◽  
Gulf Of Mexico ◽  
Monitoring System ◽  
Environmental Conditions ◽  
Net Primary Production ◽  
Opportunity To Learn ◽  
Small Scale ◽  
Small Scale Fisheries ◽  
Use Of Data ◽  
Spatio Temporal

In most small-scale fisheries (SSF), there is limited or null information about the distribution and spatial extent of the fishing grounds where the fleets operate, due to the lack of explicit spatial and temporal data. This information is key when addressing marine spatial planning and fisheries management programs for SSF. In addition to technical or biogeographic restrictions, environmental conditions in the area influence the way fishers operate. Making use of data from a pilot Vessel Monitoring System (VMS) project tested in a small-scale fleet in the Southeastern Gulf of Mexico (SGoM), for the first time in the region, we were able to learn what role environmental factors play in the distribution of potential fishing grounds for this fleet. We got tracking information of 1,608 daily fishing trips from vessels operating in four states using the VMS for 7 months. We used a correlative modeling approach to identify potential fishing grounds where this fleet operates along the SGoM, accounting for environmental variables. We assumed that environmental conditions can shape the spatial distribution of species targeted by this fleet and hence influence fishers’ operations. The results indicated that net primary production and sea surface temperature were the main drivers that shape the spatio-temporal potential distribution of fishing grounds in the study site. The approach employed here seems appropriated and opens an opportunity to learn more about the factors that define the spatial distribution of small-scale fleets and their potential fishing grounds.

Dysbaric osteonecrosis associated with decompression sickness in a fishing diver

2019 ◽  
pp. 217-220
Author(s):  
Eduardo Briceño-Souza ◽  
◽  
Nina Méndez-Domínguez ◽  
Ricardo j Cárdenas-Dajda ◽  
Walter Chin ◽  
...  
Keyword(s):  
Femoral Head ◽  
Decompression Sickness ◽  
Small Scale ◽  
Prior History ◽  
Radiological Findings ◽  
Small Scale Fisheries ◽  
Left Limb ◽  
History Of ◽  
Decompression Stress ◽  
Probable Diagnosis

Diving as a method of fishing is used worldwide in small-scale fisheries. However, one of the main causes of morbidity and mortality among fishermen is decompression sickness (DCS). We report the case of a 46-year-old male fisherman diver who presented with chronic inguinal pain that radiated to the lower left limb. Living and working in a fishing port in Yucatan, he had a prior history of DCS. A diagnosis of avascular necrosis in the left femoral head secondary to DCS was made via analysis of clinical and radiological findings. The necrosis was surgically resolved by a total hip arthroplasty. Dysbaric osteonecrosis is a more probable diagnosis. In this region fishermen undergo significant decompression stress in their daily fishing efforts. Further studies regarding prevalence of dysbaric osteonecrosis among small-scale fisheries divers are needed. In a community where DCS is endemic and has become an epidemic, as of late, the perception of this health risk remains low. Furthermore, training and decompression technique are lacking among the fishing communities.

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