Coastal largemouth bass (Micropterus salmoides) movement in response to changing salinity

Estuaries are productive, heterogeneous, and dynamic systems that support a diverse array of fishes. However, our understanding of how presumably stenohaline fishes persist in such transitional systems is limited, particularly for most fishes in tidal freshwater areas. We conducted a laboratory experiment and field investigation along an upstream–downstream salinity gradient in the Mobile–Tensaw River Delta, Alabama, USA, to test the hypothesis that age-0 largemouth bass ( Micropterus salmoides ), an economically and ecologically important freshwater species that uses low-salinity habitats in many North American estuaries, move to avoid seasonal salinity increases. To do so, we quantified changes in otolith microchemistry (e.g., Sr to Ca ratios) along the major growth axis of otoliths in both field-collected and laboratory-reared individuals. Our experiment revealed a 21-day lag time between initial salinity changes and Sr:Caotolith saturation but that Sr:Caotolith in field-collected fish reflect changes in ambient salinity. Further, contrary to our expectation, otolith microchemical analyses from spring- and fall-collected age-0 largemouth bass indicate no avoidance of increased salinity, which has potential implications for their growth and recruitment in these systems.

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Black Bass Diversity: Multidisciplinary Science for Conservation

Black Bass Diversity: Multidisciplinary Science for Conservation ◽

10.47886/9781934874400.ch25 ◽

2015 ◽

Keyword(s):

Spatial Variation ◽

Largemouth Bass ◽

Salinity Gradient ◽

Micropterus Salmoides ◽

Metabolic Cost ◽

Population Level ◽

Freshwater Species ◽

Population Demographics ◽

Bioenergetics Modeling ◽

Black Bass

Abstract.—Largemouth Bass Micropterus salmoides is typically thought of as a freshwater species, but populations occur in oligohaline portions of estuaries throughout the U.S. Atlantic and Gulf of Mexico coasts, often with popular fisheries. These coastal populations must deal with the physiological stresses associated with salinity variation and may be isolated from inland freshwater populations, increasing the potential for differentiation. To understand factors important to the ecology and management of these coastal populations, we quantified individual- and population-level parameters for Largemouth Bass across a natural salinity gradient in the Mobile-Tensaw River delta in southwestern Alabama during 2002–2009 (including population demographics, feeding ecology, movement, recruitment, and bioenergetics processes). Combining traditional mark–recapture and telemetry techniques with otolith microchemical analyses, we demonstrated that Largemouth Bass of all ages moved very little, even in response to increasing salinity (up to 15‰) in downstream areas. Large individuals were rare in our sampling across both fresh and brackish habitats (only 7 out of 9,530 individuals were >2.27 kg), and fish body condition increased downstream with increasing marine influence. Growth responses for fish across the estuary were more complex, varying with both fish age and salinity. Faster growth was observed in the brackish, downstream areas for fish ≤age 2, while growth of older fish was faster in freshwater upstream sites. Using bioenergetics modeling, we demonstrated that a complex combination of spatial variation in water temperature, prey energetic content, and metabolic cost of salinity was responsible for age-specific spatial variation in growth. Preliminary genetic analysis suggests that these coastal Largemouth Bass may differ genetically from inland fish. Coastal Largemouth Bass populations face a number of potential conservation concerns, and their management will require different approaches compared to their inland counterparts, including different goals and expectations, likely even requiring consideration as unique stocks.

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First-year growth and recruitment of coastal largemouth bass (Micropterus salmoides): spatial patterns unresolved by critical periods along a salinity gradient

Canadian Journal of Fisheries and Aquatic Sciences ◽

10.1139/f06-089 ◽

2006 ◽

Vol 63 (9) ◽

pp. 1911-1924 ◽

Cited By ~ 20

Author(s):

Adam C Peer ◽

Dennis R DeVries ◽

Russell A Wright

Keyword(s):

Largemouth Bass ◽

Salinity Gradient ◽

Micropterus Salmoides ◽

First Year ◽

Winter Mortality ◽

Heterogeneous Environments ◽

Critical Periods ◽

Hatch Date ◽

Growth Differences ◽

Food Consumed

Although critical periods often explain first-year growth and recruitment patterns of young fishes, isolated subpopulations in spatially heterogeneous environments can be influenced by distinct factors, preventing critical periods from explaining growth and recruitment for the overall population. When we explored first-year growth and recruitment variability of largemouth bass (Micropterus salmoides) along an upstream–downstream gradient in the Mobile–Tensaw Delta, Alabama, USA, growth was consistently faster at sites closest to or within brackish habitats in 2002 and 2003, despite different abiotic conditions between years. Energetic content of food consumed by faster-growing fish, particularly those furthest downstream, was greater than that for slower-growing fish. Although the timing of the switch to piscivory did not explain growth differences, the degree of piscivory was important. Hatch date had no influence on growth differences and consequently did not affect fall condition, overwinter survival, or age-1 recruitment. Contrary to several studies in freshwater systems at this latitude, first-winter mortality was neither size-selective nor excessive, and largemouth bass continued to grow through the winter. These results demonstrate that early growth can vary substantially among subpopulations in spatially heterogeneous environments and that these differences are not necessarily explained by the same factors thought to be important for freshwater largemouth bass populations.

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Balancing Fisheries Management and Water Uses for Impounded River Systems

Balancing Fisheries Management and Water Uses for Impounded River Systems ◽

10.47886/9781934874066.ch44 ◽

2008 ◽

Keyword(s):

Puerto Rico ◽

Adaptive Management ◽

Largemouth Bass ◽

Time Management ◽

Micropterus Salmoides ◽

The United States ◽

Freshwater Species ◽

Reservoir Fisheries ◽

Research Findings ◽

Management Priorities

Abstract.—Management of reservoir fisheries in Puerto Rico has been an evolving process. Puerto Rico has few native freshwater species, so reservoir fish communities have been created using nonindigenous species introduced to the island from various parts of the world. Early management efforts in reservoirs met with limited success due to low priority and limited use of reservoir fisheries, and management primarily followed temperate models focusing on largemouth bass Micropterus salmoides. Beginning in 1990, management priorities shifted and focus on reservoir fisheries began to increase. This was partly due to the increasing popularity of largemouth bass sport fishing and the organization of fishing clubs and tournament angling. An important early step was the creation of reservoir management stations, which included full-time management biologists, access ramps, and picnic and camping facilities. Cooperative research with university scientists was initiated in 1991. The ensuing research findings, changes in priorities, and establishment of on-site management biologists have combined to create an atmosphere of adaptive management, accompanied by significant changes in reservoir regulations and management protocols. In this overview, the progression of research-based adaptive management is chronicled for Puerto Rico reservoirs, which can help provide a template for management endeavors in the United States and elsewhere.

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