Anthropogenic effects including river regulation, watershed development, contamination, and fish introductions have substantially affected the majority of freshwater habitats in Europe and North America. This pattern of resource development and degradation is widespread in the tropics, and often little is known about the resources before they are lost. This article describes the freshwater resources of Puerto Rico and identifies factors that threaten conservation of native fishes. The fishes found in freshwater habitats of Puerto Rico represent a moderately diverse assemblage composed of 14 orders, 29 families, and 82 species. There are fewer than 10 species of native peripherally‐freshwater fish that require a link to marine systems. Introductions of nonindigenous species have greatly expanded fish diversity in freshwater systems, and native estuarine and marine species (18 families) also commonly enter lowland rivers and brackish lagoons. Environmental alterations, including land use and development, stream channelization, pollution, and the impoundment of rivers, combined with nonnative species introductions threaten the health and sustainability of aquatic resources in Puerto Rico. Six principal areas for attention that are important influences on the current and future status of the freshwater fish resources of Puerto Rico are identified and discussed.
– Native fish species coexist with introduced species in Puerto Rico's freshwater systems, yet competition between these species has not been evaluated. We examined the extent of diet overlap between native bigmouth sleepers Gobiomorus dormitor and introduced largemouth bass Micropterus salmoides and peacock bass Cichla ocellaris in a Puerto Rico reservoir. Bigmouth sleepers and largemouth bass exhibited an ontogenetic shift in feeding habits, whereas peacock bass were exclusively piscivorous at all sizes collected in this study. Biologically significant diet overlap was observed between large bigmouth sleepers and largemouth bass, but not between large bigmouth sleepers and peacock bass, or between large largemouth bass and adult peacock bass. No significant diet overlap in any species combination was observed in small or medium size classes. Better understanding of the ecology of these coexisting predators should lead to improved conservation of bigmouth sleepers, and improved fisheries management for all three predatory species.
The freshwater Fish Invasiveness Screening Kit (FISK) has been applied in 35 risk assessment areas in 45 countries across the six inhabited continents (11 applications using FISK v1; 25 using FISK v2). The present study aimed: to assess the breadth of FISK applications and the confidence (certainty) levels associated with the decision-support tool's 49 questions and its ability to distinguish between taxa of low-to-medium and high risk of becoming invasive, and thus provide climate-specific, generalised, calibrated thresholds for risk level categorisation; and to identify the most potentially invasive freshwater fish species on a global level. The 1973 risk assessments were carried out by 70 ? experts on 372 taxa (47 of
Declines in recreational fishing participation, underrepresentation of non-whites among the angling population, and increased urban immigration and sprawl has prompted the development of urban fishing programs. This study sought to develop profiles of anglers living within urban areas located throughout the state of Arkansas. We separated anglers based on the percentage of their fishing effort that was spent within their city of residence. Anglers that predominately fished urban waters were 34% more likely to be non-white than anglers that fished rural waters exclusively. Urban anglers placed greater importance on catch, on-site amenities, and safety than rural anglers, while rural anglers placed greater importance on the scenic beauty of a site and the ability to escape the trappings of the urban environment. Future fisheries management efforts will be dependent on the support of growing urban populations, and fisheries managers will need to strongly consider the unique needs of these constituents.
Largemouth bass Micropterus salmoides (Lacepède) catch rates decline with sustained fishing effort, even without harvest. It is unclear why declines in catch rate occur, and little research has been directed at how to improve catch rate. Learning has been proposed as a reason for declining catch rate, but has never been tested on largemouth bass. If catch rate declines because fish learn to avoid lures, periods of no fishing could be a management tool for increasing catch rate. In this study, six small impoundments with established fish populations were fished for two May to October fishing seasons to evaluate the effect of fishing effort on catch rate. Closed seasons were implemented to test whether a 2-month period of no fishing improved catch rates and to determine whether conditioning from factors other than being captured reduced catch rate. Mixed-model analysis indicated catch rate and catchability declined throughout the fishing season. Catch rate and catchability increased after a 2-month closure but soon declined to the lowest levels of the fishing season. These changes in catch rate and catchability support the conclusion of learned angler avoidance, but sustained catchability of fish not previously caught does not support that associative or social learning affected catchability.
K E Y W O R D Scatch rate, fish behaviour, fish learning, fish management, largemouth bass, small impoundments
Speckled Peacock Bass Cichla temensis are being considered for introduction into Puerto Rico to provide sportfishing opportunities and biological control for invasive New World cichlids. The proposed introduction was evaluated by following the American Fisheries Society's recommended seven‐step approach to introducing nonnative fish. This paper documents the evaluation process, which included a rapid risk screening approach using the Fish Invasiveness Screening Kit (FISK) version 2 and a series of controlled experiments on prey selection, agonistic behavior, and competition. The overall FISK score was 6 with a certainty factor of 0.84, placing the introduction in the medium‐risk category (0–18) for invasiveness. Many of the attributes elevating this species to the medium‐risk designation were the same attributes desired during species selection, including generalist feeding behavior and large body size, which are required for predation on New World cichlids. In controlled experiments, Speckled Peacock Bass consumed all cichlid species offered, suggesting that they may have potential as a biological control agent, although some selectivity in species and size was observed. Speckled Peacock Bass showed aggression toward conspecifics and other species in a mesocosm environment, but aggression generally decreased with time. There was no evidence of negative effects on Largemouth Bass Micropterus salmoides in terms of growth or condition via aggression or competition in controlled small‐pond experiments. Although some downstream movement from receiving reservoirs would be possible, downstream habitats are unsuitable for establishment of this species. The greatest risk may be unauthorized movement by anglers to other reservoirs where this species is not desired. It is the conclusion of this evaluation that Speckled Peacock Bass will consume New World cichlids and that the risks of introduction are acceptably low. Thus, introduction may proceed on a limited scale with proper scientific evaluation and public outreach directed at reducing unauthorized translocation by anglers.
Received October 12, 2016; accepted June 19, 2017 Published online August 31, 2017
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