Behavioral responses of fishes to variability in environmental conditions and habitat quality are central to population-level demographic processes. Although field surveys can correlate abundance to ...habitat variables (physiochemical, biotic, and structural), they cannot provide mechanistic explanations. Moreover, field surveys are often stratified by time or geographic criteria relevant to humans, whereas fishes stratify by habitat variables relevant to them. If mechanisms underlying behavior are not explicitly understood, conclusions based on survey data can lead to biased inferences as to species-specific habitat requirements and preferences, as well as changes in stock size occurring over time. Because physiology is the transfer function that links specific environmental conditions to behavior and fitness, we argue great gains can be made through the integration of physiology and fisheries science. These are complementary disciplines, albeit ones that generally function at very different temporal and spatial scales, as well as different levels of biological organization. We argue more specifically that integrating physiological approaches with behavioral studies and traditional fisheries survey data (where each approach develops hypotheses to be tested in the other) can mechanistically link processes from cells through populations to place fisheries management in an appropriate ecosystem context. We further contend that population- and species-specific mechanistic understanding of physiological abilities and tolerances can significantly help to: improve stock assessments, describe essential fish habitat, predict rates of post-release mortality, develop effective bycatch reduction strategies, and forecast the population effects of increases in global temperatures and ocean acidification.
We assessed the taxonomic diversity, geographic distributions, life history, ecology and fisheries of tarpons, ladyfishes and bonefishes (members of the subdivision Elopomorpha), which share many ...life history and habitat use characteristics that make them vulnerable to environmental and anthropogenic stresses in coastal environments. This assessment of Red List status for the International Union for the Conservation of Nature reveals three species considered near threatened or vulnerable, three species of least concern, and 11 data‐deficient species. Although the taxonomy of tarpons appears stable, it is less so for ladyfishes and bonefishes. In aggregate, these species are distributed circumtropically and foray into temperate zones. Although they spawn in marine habitats, larvae of many species disperse into estuarine habitats, which are declining in area or degrading in quality. Several species support high‐value recreational fisheries, or culturally important small‐scale commercial and artisanal fisheries. Nonetheless, no formal stock assessment exists for any species, so improved data collection, information sharing and assessment techniques should facilitate socio‐economic development of individual fisheries. Catch‐and‐release recreational fisheries that promote conservation of tarpon and bonefishes in some regions are promising models to improve the conservation status of these fishes elsewhere, as well as the economic development of these fishing communities. Most tarpons, ladyfishes and bonefishes likely face significant challenges from anthropogenically mediated habitat loss and alteration, and several are vulnerable to both habitat degradation and overfishing. Broader protection and enhancements to fisheries habitat in all regions will benefit these as well as many other coastal fishery species.
Dietary insufficiencies have been well documented to decrease growth rates and survival (and therefore overall production) in fish aquaculture. By contrast, the effects of dietary insufficiencies on ...the sensory biology of cultured fish remains largely unstudied. Diets based solely on plant protein sources could have advantages over fish-based diets because of the cost and ecological effects of the latter, but plant proteins lack the amino acid taurine. Adequate levels of taurine are, however, necessary for the development of a fully functional visual system in mammals. As part of ongoing studies to determine the suitability of plant-based diets, we investigated the effects of normal and reduced taurine dietary levels on retinal anatomy and function in European sea bass (Dicentrarchus labrax). We could not demonstrate any effects of dietary taurine level on retinal anatomy, nor the functional properties of luminous sensitivity and temporal resolution (measured as flicker fusion frequency). We did, however, find an effect on spectral sensitivity. The peak of spectral sensitivity of individuals fed a 5% taurine diet was rightward shifted (i.e., towards longer wavelengths) relative to that of fish fed a 0% or 1.5% taurine diet. This difference in in spectral sensitivity was due to a relatively lower level of middle wavelength pigment (maximum absorbance .500 nm) in fish fed a 5% taurine diet. Changes in spectral sensitivity resulting from diets containing different taurine levels are unlikely to be detrimental to fish destined for market, but could be in fishes that are being reared for stock enhancement programs.
The movement ecology of fishes Cooke, Steven J.; Bergman, Jordanna N.; Twardek, William M. ...
Journal of fish biology,
October 2022, 2022-10-00, 20221001, Letnik:
101, Številka:
4
Journal Article
Recenzirano
Odprti dostop
Movement of fishes in the aquatic realm is fundamental to their ecology and survival. Movement can be driven by a variety of biological, physiological and environmental factors occurring across all ...spatial and temporal scales. The intrinsic capacity of movement to impact fish individually (e.g., foraging) with potential knock‐on effects throughout the ecosystem (e.g., food web dynamics) has garnered considerable interest in the field of movement ecology. The advancement of technology in recent decades, in combination with ever‐growing threats to freshwater and marine systems, has further spurred empirical research and theoretical considerations. Given the rapid expansion within the field of movement ecology and its significant role in informing management and conservation efforts, a contemporary and multidisciplinary review about the various components influencing movement is outstanding. Using an established conceptual framework for movement ecology as a guide (i.e., Nathan et al., 2008: 19052), we synthesized the environmental and individual factors that affect the movement of fishes. Specifically, internal (e.g., energy acquisition, endocrinology, and homeostasis) and external (biotic and abiotic) environmental elements are discussed, as well as the different processes that influence individual‐level (or population) decisions, such as navigation cues, motion capacity, propagation characteristics and group behaviours. In addition to environmental drivers and individual movement factors, we also explored how associated strategies help survival by optimizing physiological and other biological states. Next, we identified how movement ecology is increasingly being incorporated into management and conservation by highlighting the inherent benefits that spatio‐temporal fish behaviour imbues into policy, regulatory, and remediation planning. Finally, we considered the future of movement ecology by evaluating ongoing technological innovations and both the challenges and opportunities that these advancements create for scientists and managers. As aquatic ecosystems continue to face alarming climate (and other human‐driven) issues that impact animal movements, the comprehensive and multidisciplinary assessment of movement ecology will be instrumental in developing plans to guide research and promote sustainability measures for aquatic resources.
MicroRNAs (miRNAs) are epigenetic markers with a key role in post-transcriptional gene regulation. Several studies have described the dysregulation of miRNAs in temperature and hypoxic stress ...responses of marine organisms, but their role in the response to acidification conditions has remained relatively underexplored. We investigated the differential expression of miRNAs in whole brain tissue of Arctic cod (
Boregogadus
saida) exposed to elevated aqueous CO
2
levels representative of future climate change predictions. We detected the expression of 17 miRNAs of interest that are either directly or indirectly associated with reduced auditory performance; 12 of the 17 miRNAs showed significant differential expression in high treatment vs. low (control) aqueous CO
2
conditions. Target gene predictions indicated that these miRNAs are likely involved with inner ear maintenance, hair cell degradation, age-related hearing loss, neural inflammation, and injury. The highest differential expression was observed in mir-135b, which is linked with increased neural inflammation and injury that may be associated with neurosensory dysfunction. Collectively, these results elucidate the contributions of miRNA mechanisms underlying CO
2
-induced sensory deficits in fishes facing abiotic environmental change and suggest strong potential for this approach to yield novel insights into the mechanistic effects of climate change on marine organisms.
Indo-Pacific lionfish (
Pterois
spp.) have become established throughout the Caribbean and the coastal regions of the Gulf of Mexico and western Atlantic Ocean from North Carolina to central Brazil. ...Lionfish may also invade estuaries, as they tolerate salinities down to 4‰. We hypothesize that the functional characteristics of their visual system (which evolved in the clear tropical waters of the Indo-Pacific) or their inability to tolerate hypoxia will limit the capacity of lionfish to occupy these areas. We assessed the former with corneal electroretinography and the latter with intermittent-flow respirometry. The luminous sensitivity, temporal resolution (quantified as flicker fusion frequency), and spectral sensitivity of the lionfish visual system are like those of native piscivores, indicating that their visual system will be functional under estuarine photic conditions and allow lionfish to be effective piscivores. In contrast, acute exposure to reduced oxygen levels (equivalent to those commonly occurring in mid-Atlantic and Gulf of Mexico estuaries) exceeded the physiological tolerances of lionfish. We therefore conclude that hypoxia will control or limit estuarine invasion.
Istiophorid billfishes are targeted in recreational fisheries throughout the tropical and subtropical waters of the world's oceans. Over the past thirty years, changes in management regulations and ...increased angler conservation awareness have resulted in an increasing proportion of the billfish catch being released alive, and in many areas the fishery is principally catch-and-release. However, the fate of released fish, and thus the fishing mortality associated with the recreational fishery, is not well understood. Some insights into post-release mortality of billfishes caught in the recreational fishery have been gained from analyses of conventional tag data, hooking location information, and acoustic tracking data. Over the past 10 years pop-up satellite archival tags (PSATs) have been used to specifically estimate post-release mortality for a limited number billfish species. Extrapolation of the results of these limited studies throughout the various recreational billfish fisheries is not prudent due to potential influences of different species, areas, seasons, fishing styles, and hook types. The current high cost of PSATs presents a significant obstacle to evaluating the effect of these variables on rates of post-release survival. Nonetheless, the results of the few studies to date have had an important impact on fisheries management and the behavior of recreational anglers.
Migration is a widespread but highly diverse component of many animal life histories. Fish migrate throughout the world's oceans, within lakes and rivers, and between the two realms, transporting ...matter, energy, and other species (e.g., microbes) across boundaries. Migration is therefore a process responsible for myriad ecosystem services. Many human populations depend on the presence of predictable migrations of fish for their subsistence and livelihoods. Although much research has focused on fish migration, many questions remain in our rapidly changing world. We assembled a diverse team of fundamental and applied scientists who study fish migrations in marine and freshwater environments to identify pressing unanswered questions. Our exercise revealed questions within themes related to understanding the migrating individual's internal state, navigational mechanisms, locomotor capabilities, external drivers of migration, the threats confronting migratory fish including climate change, and the role of migration. In addition, we identified key requirements for aquatic animal management, restoration, policy, and governance. Lessons revealed included the difficulties in generalizing among species and populations, and in understanding the levels of connectivity facilitated by migrating fishes. We conclude by identifying priority research needed for assuring a sustainable future for migratory fishes.
Maintaining optimal visual performance is a difficult task in photodynamic coastal and estuarine waters because of the unavoidable tradeoffs between luminous sensitivity and spatial and temporal ...resolution, yet the visual systems of coastal piscivores remain understudied despite differences in their ecomorphology and microhabitat use. We therefore used electroretinographic techniques to describe the light sensitivities, temporal properties and spectral sensitivities of the visual systems of four piscivorous fishes common to coastal and estuarine waters of the western North Atlantic: striped bass (Morone saxatilis), bluefish (Pomatomus saltatrix), summer flounder (Paralichthys dentatus) and cobia (Rachycentron canadum). Benthic summer flounder exhibited higher luminous sensitivity and broader dynamic range than the three pelagic foragers. The former were at the more sensitive end of an emerging continuum for coastal fishes. By contrast, pelagic species were comparatively less sensitive, but showed larger day-night differences, consistent with their use of diel light-variant photic habitats. Flicker fusion frequency experiments revealed significant interspecific differences at maximum intensities that correlated with lifestyle and habitat. Spectral responses of most species spanned 400-610 nm, with significant day-night differences in striped bass and bluefish. Anadromous striped bass additionally responded to longer wavelengths, similar to many freshwater fishes. Collectively, these results suggest that pelagic piscivores are well adapted to bright photoclimates, which may be at odds with the modern state of eutrified coastal and estuarine waters that they utilize. Recent anthropogenic degradation of water quality in coastal environments, at a pace faster than the evolution of visual systems, may impede visually foraging piscivores, change selected prey, and eventually restructure ecosystems.
Populations of tunas, billfishes and pelagic sharks are fished at or over capacity in many regions of the world. They are captured by directed commercial and recreational fisheries (the latter of ...which often promote catch and release) or as incidental catch or bycatch in commercial fisheries. Population assessments of pelagic fishes typically incorporate catch-per-unit-effort time-series data from commercial and recreational fisheries; however, there have been notable changes in target species, areas fished and depth-specific gear deployments over the years that may have affected catchability. Some regional fisheries management organizations take into account the effects of time- and area-specific changes in the behaviours of fish and fishers, as well as fishing gear, to standardize catch-per-unit-effort indices and refine population estimates. However, estimates of changes in stock size over time may be very sensitive to underlying assumptions of the effects of oceanographic conditions and prey distribution on the horizontal and vertical movement patterns and distribution of pelagic fishes. Effective management and successful conservation of pelagic fishes requires a mechanistic understanding of their physiological and behavioural responses to environmental variability, potential for interaction with commercial and recreational fishing gear, and the capture process. The interdisciplinary field of conservation physiology can provide insights into pelagic fish demography and ecology (including environmental relationships and interspecific interactions) by uniting the complementary expertise and skills of fish physiologists and fisheries scientists. The iterative testing by one discipline of hypotheses generated by the other can span the fundamental-applied science continuum, leading to the development of robust insights supporting informed management. The resulting species-specific understanding of physiological abilities and tolerances can help to improve stock assessments, develop effective bycatch-reduction strategies, predict rates of post-release mortality, and forecast the population effects of environmental change. In this synthesis, we review several examples of these interdisciplinary collaborations that currently benefit pelagic fisheries management. Key words: Bycatch, cardiorespiratory, Fry paradigm, pelagic fishes, post-release survival Editor: Craig Franklin Received 27 July 2015; Revised 9 November 2015; accepted 15 November 2015 doi: 10.1093/conphys/cov059
PDF
