Environmental Biology of Fishes最新文献

Harriotta avia sp. nov., a new species of long-nose chimaera (Holocephali: Chimaeriformes: Rhinochimaeridae), is described from specimens collected off New Zealand in the Southwest Pacific Ocean. The species is distinguished from its congeners by a combination of the following characters: elongated, narrow and depressed snout up to 56% BDL; long, slender trunk; beak-like vomerine tooth plate; large eye, length 8–12% BDL and height 5–7% BDL; long dorsal spine reaching slightly beyond apex of the dorsal fin; and slender rod-like pelvic claspers. The skin is deciduous, and uniform chocolate brown when intact. Harriotta avia sp. nov. is also distinguished from other Harriotta species based on DNA sequence divergence of the NADH2 gene. Harriotta avia sp. nov. is reported from the New Zealand-Australian region. Conclusions here show that Harriotta raleighana, a presumed globally distributed species, likely comprises several species and the genus Harriotta warrants a revision with specimens representing all ocean basins.

Goldeye are a species of hiodontid native to northern North America. In the Missouri River reservoirs of South Dakota, Lake Oahe and Lake Sharpe, goldeye populations have been documented as bycatch during standardized surveys with limited attention given to their long-term abundance patterns or role in the fishery. However, in recent years, noticeable declines in goldeye abundance have led to investigating the current population status along with what factors could be influencing goldeye densities. We sought to examine relative abundance trends from 2014 to 2023 and describe current population dynamics (i.e., size structure, relative weight (W_r), age, growth, and mortality) of these two Missouri River mainstem reservoirs. In Lake Oahe, the median total length of sampled goldeye was 372 mm (minimum = 274 mm; maximum = 474 mm) with an estimated observed maximum age of 7. In Lake Sharpe, the median total length of sampled goldeye was 392 mm (minimum = 284; maximum = 435 mm) with an estimated observed maximum age of 5. Goldeye W_r averaged 104 in Lake Oahe and 96 in Lake Sharpe indicating good body condition. We fit von Bertalanffy growth models to back-calculated length at annulus formation for both Lake Oahe (L_∞ = 482 mm, K = 0.18, and t₀ = − 2.96) and Lake Sharpe (L_∞ = 430 mm, K = 0.27, and t₀ = − 2.69) to evaluate goldeye growth. Lake Oahe estimated annual mortality was 27.2%. We fit GLMs and used AICc to evaluate the relationship between goldeye CPE and lake elevation, growing degree days (GDD), and predator CPE and found weak relationships between goldeye abundance and lake elevation and GDD in the first study to attempt to examine relationships between goldeye abundance and environmental variables potentially impacting dynamic rate functions. Our work highlights the paucity of basic life history information for goldeye and the lack of harvest regulations across its native range.

White sucker (Catostomus commersonii) is a large-bodied benthic fish species that is found across a broad geographic region in North America. Often overlooked, white suckers are an integral component of aquatic ecosystems in their role as the dominant nearshore benthivore in many lakes. Few detailed field investigations on habitat use and thermal occupancy of white sucker exist, limiting our ability to predict the risk of habitat loss from development and climate warming for this cool-water species. Here we investigated seasonal depth, temperature and spatial occupancy patterns of white suckers in a lake located in northern Ontario, Canada. Using a combination of positioning acoustic telemetry and environmental data, we determined depth and space use patterns, seasonal temperature preference indices, and the affinity of white sucker to the lake bottom (i.e., benthic habitat) over a year long period. We found that the white suckers were consistently observed in shallow waters (< 10 m depth) and near the lake bottom across all seasons but were positioned slightly deeper in the winter. The tagged white suckers showed a strong temperature selection preference for thermal habitat between 10 and 16 °C during the open-water seasons and tended to avoid cold (< 6 °C) thermal habitat. Space use patterns, calculated using kernel utilization distributions, and daily movement rates were surprisingly consistent across all seasons, with regular occupancy of only some nearshore areas. This study highlights a highly restrictive pattern of habitat use by white sucker that is consistent across seasons, suggesting that this generalist species may be more vulnerable to anthropogenic disturbance than previously thought.

Recruitment is the addition of individuals to a population that generally occurs in the early juvenile phase, which is key to understanding the dynamics of reef fish communities. Through visual censuses in three climatic seasons (dry, rainy, and northerly winds) between 2017 and 2020, the analysis of seasonal and interannual variations in the abundance of fish recruits in a reef lagoon (Mahahual, Quintana Roo, México) was carried out. Temporality was analyzed using average recruit density graphs and multivariate analyses (multivariate ANOVA, ANOSIM, and RDA) to assess composition differences between year and season levels. A total of 9326 recruits were registered, belonging to 36 species and 8 fish families. The Labridae had the greatest number of recruits, followed by Pomacentridae and Scaridae. The recruits were more abundant in the dry season when the average temperatures were 27.50–27.87 °C; meanwhile, they presented a lower abundance in the northerly wind season when the temperature was lower (26.7 °C). The most abundant species was Thalassoma bifasciatum (138.72 recruits/100 m²), followed by Abudefduf saxatilis (100.05 recruits/100 m²) and Halichoeres bivittatus (45.94 recruits/100 m²). The multifactorial ANOVA for the average density and the ANOSIM for the composition of recruits did not show significant differences for the year factor, but they did for the season factor. RDA indicated that the greatest average dissimilarity existed between the dry season and the other two climatic seasons. The results of this study highlight the importance of recruitment during the warm months and the refuge offered by the lagoon for the maintenance of reef fish populations.

The bristlenose pleco (Ancistrus cirrhosus) is a species of Loricariidae armored catfish that breathes air using its highly vascularized stomach when faced with hypoxic aquatic environments. The main goals of this study were to determine the developmental onset of air breathing and air-breathing behavior in A. cirrhosus from juveniles to adults. Developing juveniles reach functional maturity within 4 to 6 months of hatching, growing to an adult length of 8 to 10 cm. To examine the timing of the developmental onset of air breathing, we tested for air-breathing behavior in juveniles beginning at 1 cm in length up through adults at 8 cm in length by exposing each fish to an acute gradual decrease in aquatic oxygen content from 100% air saturation down to 8% air saturation over a 50-min period. Juvenile fish first began to breathe air at body lengths between 2.1 and 3 cm and masses of 1.1 and 2 g. Fish with body lengths above 3 cm all breathed air when hypoxia challenged. In fish that breathed air, there was a weak negative correlation between fish length and % air saturation at which air breathing began. Fish were also exposed to an acute bout of 15% air saturation for 60 min, and breathing behavior was observed. Fish exposed to 60 min acute 15% air saturation exhibited a negative correlation between the frequency of air breathing and fish length. The developing A. cirrhosus can take advantage of the aerial environment once they reach 3 cm in length and 2 g when exposed to aquatic hypoxia. Prior to this size, these animals would potentially succumb to severe aquatic hypoxia without the ability to breathe air.

At the end of the Inuit summer, anadromous Arctic char (Salvelinus alpinus) migrate toward Tasirjuarusik Lake (Kangirsuk, Nunavik, Quebec). They sustain subsistence fishing during the upstream migration. However, during the winter, local Inuit fishers have been unsuccessful in catching Arctic char in this lake, but catches do resume in late spring. The Kangirsuk hunters and fishers’ association, Uumajulirijikkut Kangirsumi, initiated a telemetry study to assess (1) if the Arctic char were overwintering in the lake and (2) if the fish behavior during winter and spring was linked to environmental characteristics (temperature, oxygen, or ice). Eight Arctic char were tagged with acoustic transmitters during their upstream migration, and passive receivers were deployed throughout the lake continuously for 2 years. Five of the tagged fish overwintered in the lake, where they remained inactive for approximately 8 months. The difficulty of catching them in winter is likely due to their low activity level combined with the large areas of littoral zones (selected habitat) in this lake. A significant increase in the activity level of the tagged Arctic char occurred simultaneously with the onset of snowmelt runoff until the complete mixing of the lake. Char left the lake at peak discharge, coinciding with the ice breakup at the lake outlet. The results of this collaborative research, led by the community with locally grounded questions, align with and complement the observations of fishers. Despite the limited number of tagged fish due to community concerns about animal well-being, the results illustrate different migration patterns within this population and shed light on the environmental triggers that lead to the resumption of char activity in spring.

Due to disturbance-driven phase shifts on coral reefs, sponges are an increasingly important microhabitat for reef-dwelling organisms, particularly throughout the Caribbean. The abundance of sponge-dwelling species is expected to be heavily influenced by their degree of habitat specialization, as well as the distribution and morphology of potential host sponges. We conducted surveys along the fringing reefs of Curaçao to test how host sponge community composition and morphology drive occupancy patterns of the yellowline goby (Elacatinus horsti). The assemblage of goby-occupied sponges varied across the island, representing habitat heterogeneity across surveyed sites. We found E. horsti to be a sponge generalist, commonly occupying three species: Aplysina lacunosa, Aplysina archeri, and Neofibularia nolitangere, though all host species had some unoccupied sponges. A variable related to overall sponge size—maximum sponge height—significantly influenced the likelihood of goby occupancy. Goby group size in a sponge was also influenced by maximum sponge height along with the number of oscula and the species of host sponge. Specifically, group sizes were bigger in larger sponges with more openings, and the noxious sponge N. nolitangere hosted groups that were estimated to be 2.6–9.0 times larger than groups in other sponges when accounting for host morphology. Therefore, for these site-attached fish, the opportunity for conspecific interactions varies across different hosts. Collectively, our findings lay the groundwork for future investigations into the ecological trade-offs and fitness consequences of occupying distinct host species and examining the nature of fish-sponge symbioses.

Smallmouth buffalo (Ictiobus bubalus Rafinesque) are a large-bodied fish highly valued and commercially exploited across most of their range. Despite this, relatively little is known of their population demographics compared to other exploited species. To fill these knowledge gaps, we analyzed two independent long-term datasets (30 and 57 years, respectively) and population demographic data (age structure, growth, mortality, age at maturity, and recruitment) from multiple pools of the Upper Mississippi River System (UMRS) and Illinois River (Illinois, USA). Long-term data (30-year dataset) generally show downward trends or significant declines in catch per unit effort in the UMRS, while the 57-year dataset shows a stable trend or a significant increase in the Illinois River. The oldest smallmouth buffalo were estimated to be 39 years old, with nearly every pool sampled having individuals estimated to exceed 30 years of age. Except for Pool 13 of the UMRS, 90% of smallmouth buffalo were estimated to mature between 411 and 470 mm in length or between 8.7 and 11.2 years old. Recruitment was variable: strong year classes were generally preceded by multiple years of weak year classes. Our results indicate that the smallmouth buffalo population may be stable in portions of the UMRS and Illinois River systems, but significant declines in the northern extent of the UMRS may warrant conservation concern. Recent research into ages of buffalofishes shows that consideration should be given to the idea that the UMRS population could be age truncated. Results also emphasize the importance of long-term data and the ability to show changes in exploited populations over time.

Carbon (δ¹³C) and nitrogen (δ¹⁵N) stable isotopes (SI) serve as natural markers for evaluating fish food sources. However, interpreting SI isotope values in newly hatched fish becomes intricate due to the transfer of maternal resources during early development (egg, larvae). This research investigates maternal influences on neotropical freshwater fish larvae growth through SI analysis, focusing on the pacú fish (Piaractus mesopotamicus). The study utilizes a commercial inert feed to assess carbon and nitrogen contributions to larval tissue growth while evaluating the turnover rate, providing valuable insights into early-life nutritional dynamics. Both SI exhibit variations during larval development, following a chronological pattern corresponding to ontogeny, with a significant shift at 13 days after hatching (DAH). Maternal transmission significantly influences isotopic signatures in early larval stages, showing linear correlations between isotopic ratios and standard length (SL) until 15 DAH. C:N ratios decrease from 6.3 ± 0.1 at 0 DAH to 4.2 ± 0.1 at 13 DAH. The isotopic composition of maternal origin aligns with egg stage values, emphasizing the stability of maternal transmission. Under experimental conditions, elemental carbon half-life in tissue (t₅₀) is 6.44 days, and nitrogen t₅₀ is 3.82 days. Maternal isotopic ratios in initial larval development stages offer a potential method for estimating nutritional tracers in field-collected eggs, contributing to understanding the role of freshwater nurseries in comprehending migratory routes, critical hatchery areas, and stock assessment of neotropical migratory fishes. This research provides valuable insights for fisheries management of continental fish species, emphasizing the efficiency of using maternal transmission as an indicator for estimating contributions from nurseries to fish stock recruitment.

Research efforts focusing on salmonid populations have highlighted the need to better understand demographic parameters for the fry and parr life stages. Monitoring these small fish presents a challenge because negative effects from handling and tagging can bias subsequent parameter estimates. Removal models and associated sampling designs represent one class of mark-recapture models with potential to be applied to very small juvenile salmon, yet existing methods associated with removal studies are not well-suited for all study environments. For example, populations residing in large storage reservoirs may yield low capture probabilities when subjected to removal sampling, making unbiased estimation of survival using traditional removal models difficult. To address this limitation, we developed a sampling design and associated model using parentage-based tagging in hatchery-raised juvenile Chinook salmon (Oncorhynchus tshawytscha) to estimate survival over a 2-year study period in a large storage reservoir in western Oregon, USA. Individual fish were identified to family groups, serving as replicate batch marks in a robust design removal model framework. Results from a simulation suggested that parameter estimates were unbiased even at very low capture probabilities, although the use of model constraints (i.e., covariates or constant parameter values) was necessary to achieve this. Model fitting to field data supported a trend in survival over time, with survival increasing with time since release in the first study year but decreasing in the second.