Finfish Community Research Articles

Nekton use of oligohaline Phragmites australis and Spartina alterniflora marsh in Chesapeake Bay and North Carolina, USA

Oligohaline Phragmites australis and Spartina alterniflora marshes with similar physical conditions were examined within two different geographic regions: 1) related to marsh nekton and marsh-edge finfish species abundance, biomass and community structure, 2) to determine whether marsh functional patterns are consistent over large-scale geographic settings, and 3) to assess consistency of nekton use for each macrophyte type between geographic regions. Few significant differences regarding abundance, biomass, community structure, and catch composition between P. australis and S. alterniflora marshes for marsh nekton and marsh-edge finfish species were observed. P. australis and S. alterniflora marshes, regardless of geographic region, provided similar functions for marsh nekton and estuarine finfish communities. However, differences between Chesapeake Bay and North Carolina geographic regions for marsh nekton use were pronounced. Significantly more nekton species utilized P. australis and S. alterniflora marshes in North Carolina versus Chesapeake Bay. Also, the abundance of seven of 12 marsh nekton species common to both regions within S. alterniflora marshes, and four of 12 species within P. australis marshes, differed significantly between regions. It is important to consider at what point differences between estuarine habitats warrant the selection of one functional habitat over another, or conversion of functional habitat for restoration of another. Instead of determinations based on one or a few species of interest, clearly defined criteria should be used to determine necessity for replacement of one habitat type for another, and these should consider ecological values and attributes necessary for ecosystem function.

Macrofaunal Assemblages on Oyster Aquaculture and Rock Reef Habitat in Long Island Sound

AbstractTrap sampling was used to survey the relative abundance of juvenile fish and invertebrates near three habitats including an off‐bottom oyster cage farm (cage farm), a traditional on‐bottom oyster culture area (shell bottom), and a natural cobble and boulder reef (rock reef) in a coastal embayment in Long Island Sound near Milford, Connecticut. Ten traps, deployed on two subsites within each habitat (20/habitat), were allowed to soak for ~24 hours, two to three times per week, from June through September 2016. The assemblages of juvenile finfish appeared to be similar on the cage farm and rock reef, while the composition of the invertebrate community was more variable among the three habitats. These preliminary observations suggest that oyster cage farms may provide functional habitat that is populated by structure‐oriented finfish communities similar to those that are found on natural rock reefs in Long Island Sound.

Application of Environmental DNA Metabarcoding to Spatiotemporal Finfish Community Assessment in a Temperate Embayment

Environmental DNA (eDNA) metabarcoding was used to characterize finfish communities in the nearshore estuarine environment. Monthly sampling was conducted June - August 2017 at two sites with structured habitats: a natural rock reef and a shellfish aquaculture farm within the same coastal embayment of Long Island Sound, CT, USA. Seventeen common and 25 rare finfish taxa were detected using eDNA metabarcoding. Incomplete status of reference sequence databases for finfish species was identified as a methodological challenge. Confidence in molecular identification was improved appreciably through the use of publicly-available data obtained from local trawling and seining surveys. Comparison between eDNA metabarcoding and trawling surveys on 6/27/2017, the only day when both data types were available, revealed more finfish species detected by eDNA metabarcoding. The high sensitivity of eDNA metabarcoding detected finfish species rarely observed in traditional surveys and showed the potential for this methodology to augment existing literature for finfish species distribution patterns and invasive species detection. Non-metric multidimensional scaling (NMS) analysis of finfish communities achieved a low-stress, 2D solution, and revealed greater variation between samples collected from different months than samples collected from the two habitats. Similarly, permutational analysis of variance (PERMANOVA) found both month and the interaction term (month x site) significant, with the latter identifying site as significant only in July and August. Different finfish assemblages were significantly associated with each axis, axes representing temporal and spatial variations, respectively. Additionally, polycarbonate and nylon filters were compared to optimize the sampling method; finfish communities retrieved using the 2 types of filters were statistically indistinguishable by NMS analysis, although the filtration time for nylon filters was shorter. If the objective is to detect rare species, nylon filters are recommended over polycarbonate filters because of higher capture rates of rare taxa. Our study demonstrates the potential for applying eDNA metabarcoding as a stand-alone method to conduct finfish surveys with high sensitivity.

Salt Marsh Habitat Size and Location Do Matter: the Influence of Salt Marsh Size and Landscape Setting on Nekton and Estuarine Finfish Community Structure

Do estuarine habitat size and landscape setting influence community structure and the habitats’ ability to support certain species? Small-island marshes (SIM) ~ 400–1000 m2 and large-island marshes (LIM) ~ 3000–10,000 m2 were paired with expansive-fringing marshes (EFM), each > 76,000 m2 in size, to assess nekton and estuarine finfish use related to marsh habitat size and factors contributing to use patterns. Marsh-dependent nekton, which have limited larval and adult dispersal ability, demonstrated density patterns directly related to marsh area size, which was indicative of available interior marsh space, with population persistence subject to minimum marsh size thresholds. Estuarine-resident nekton typically demonstrated negative density to marsh size patterns representing increased use of marshes with low area:perimeter ratios, suggesting the importance of marsh edge. SIM and EFM had significantly higher species richness and densities of estuarine-resident nekton species over LIM demonstrating area:perimeter-related marsh edge influence on use by nekton from the surrounding open-water habitats inundating SIM with associated species, while the more complex nature of EFM, based on size, allowed accumulation of species and provided adequate resources for populations. Estuarine landscape-level factors for individual sites were more influential in determining finfish marsh site use than habitat-specific factors. Island marshes are significant marsh/open-water trophic exchange areas because of the greater accessibility to island marshes versus EFM for larger predator fishes.

Maximizing the benefits of oyster reef restoration for finfish and their fisheries

AbstractGlobal declines in oyster reefs have resulted in reduced habitat heterogeneity, extent and quality for some coastal finfish, potentially reducing fish populations and catches. It is well established that habitat restoration results in higher finfish biomass and diversity where oyster reefs replace bare substrata. Therefore, restoring oyster reefs with a view to also improving fish stocks is often a key goal of oyster restoration. However, the principles of habitat quality, ecological connectivity and broader ecosystem management are poorly integrated within oyster reef restoration ecology, but such principles may be instructive in enhancing the benefits of projects on fish populations throughout estuarine seascapes. This manuscript presents a framework for projects seeking to restore both oyster reef habitat and finfish communities. Structurally and biologically complex oyster reefs, comprising both oysters and other invertebrates, are required to provide shelter, food and nursery services to fish. By carefully considering site selection at seascape scales (km to 10s of km), restoration can enhance the network of habitat available to fish and potentially increase the overall carrying capacity of the estuary. Managers of estuaries that now include restored oyster reefs should implement fisheries management plans and consider the effects of management actions broadly throughout catchments; failing to do so may jeopardize gains in fish yields. Management decisions must be adaptable, responding to key criteria in thorough monitoring programs. Integrating these ecological and coastal management concepts into oyster reef restoration will enhance outcomes for fishes and increase stakeholder engagement and cost‐effectiveness.

Spawning delays of northern capelin (Mallotus villosus) and recovery dynamics: A mismatch with ice-mediated spring bloom?

The capelin stock off the northeast coast of Newfoundland and southern Labrador collapsed in the early 1990s along with most of the finfish community. Among a host of concomitant physical and behavioral changes was the onset of delayed spawning, a phenomenon that has persisted for over two decades. From the mid-1990s onward, the Newfoundland and Labrador shelf has been warming with ice levels reduced in most years, generally leading to earlier spring plankton blooms. The delayed spawns and earlier blooms have resulted in an increased mismatch between plankton production and larval emergence, which we hypothesized could result in reduced early-life survival and prolonged stock recovery. Among indices associated with the mismatch, including time between blooms and spawning, composition and abundance of zooplankton during early ontogeny, and sea surface temperature and ice coverage, potential linkages were found with first year capelin survival. Increased capelin productivity in recent years has been associated with an increase in preferable and total zooplankton abundance and a decreasing trend in the mismatch with the spring bloom. A generalized linear model incorporating a match–mismatch index and stage I–IV calanus copepods explained 82% of the variance associated with annual age 0 capelin abundance estimates since stock collapse. A central mechanism underlying improvements in capelin productivity appears to be a general reduction in ice coverage associated with a recent warm oceanographic regime that reached record high levels in 2011.

Aspects of the Ecology of the Grass Mat Finfish Community of Kugbo Creek in Niger Delta, Nigeria

A study on the grass-mat finfish community of Kugbo Creek was done in 3 zones of Kugbo Creek for 24 months. Biweekly samples obtained from the zones showed a total of 3192 individual finfish belonging to 26 species and 14 families. Occurrence among zones was 25 species were found in freshwater zone 1, 24 in fresh/brackish water zone 2 and 4 species in brackish water zone 3 respectively. The dominant finfish species was Dormitator pleurops with 451 individuals. The habit host rear species of Nannocharax niloticus, Karibia karibensis, Thysia ansorgii, Marcrousenius thuysi and Mastacablus loennbergi. Juveniles of Calamoichthys calabaricus, Heterotis niloticus, Channa obscura, Polycentropsis abreviata, Heterobranchus longifilis and Mastaceblus loennbergi, were also caught in the habit. This shows that some fish undergo part of their developmental stages in the grass mat habitat, including some with high commercial values. Some species such as Gymnacus niloticus and Hepsetus odoe build their spawning nest in the grass mat where they lay eggs during breeding season. Virtually all other fresh water fish species also visit the habitat either in search of food or shelter at one time or the other as most stomach content compositions are also found in the grass mat habitat, e.g. Papyranocranus afar and Xenomystus nigri, . The habitat sheltered endangered finfish species such as Neolebias powelli, that was caught during sampling. These suggest the importance and sensitive nature of the

Testing systemic fishing responses with ecosystem indicators

Successful implementation of Ecosystem Based Fisheries Management (EBFM) requires practical methods of translating information on system status into management actions. Threshold values in ecosystem indicators have been demonstrated to provide insight for characterizing change points in marine ecosystems and suggested as reference points for EBFM. We used a guild based multispecies simulation model of the Georges Bank finfish community to quantify tradeoffs and changes among values for proposed ecological indicators given alternative fishing scenarios, and tested the performance of indicator-based approaches for setting system ceilings on annual catches.Values for ecosystem indicators were sensitive to the exploitation rates on guilds, with total biomass of the community being most sensitive to groundfish exploitation rate. Setting ceilings on system-wide annual catches was successful in constraining values for indicators and revealed levels of system catch associated with indicator change. Community composition indicators showed catch thresholds lower than provided by the total biomass indicator. Ceilings based on community composition indicators more frequently resulted in higher yields and fewer species being overfished than when ceilings were set using total biomass or when no ceiling was in place.Simulations demonstrated that threshold values in ecosystem indicators could be used to determine reference points in an EBFM context. The broad ranges for threshold values obtained demonstrates the sensitivity of such methods to exploitation history, underscoring the need to both incorporate expert knowledge and relate reference point determination to management objectives.

Benthic‐pelagic coupling in a temperate inner continental shelf fish assemblage

The hypothesis that demersal finfish production dependence on pelagic food webs decreased with seabed habitat affinity and fish size was tested using stable isotope and stomach contents data from 17 finfish species collected during summer months from the inner continental shelf of the U.S. mid‐Atlantic coast. Trophic dependence on pelagic prey was generally lower among species with higher affinities for bottom habitats, but even species morphologically adapted for bottom feeding benefited from pelagic production via diel vertical migration of prey. There was a consistent pattern of declining reliance on pelagic food webs with increasing fish size, although the relationship between size and trophic sources varied among functional groups within the fish community. Overall, pelagic primary production during the summer was an important basal energy source for the demersal finfish community in this coastal ocean habitat (d 20 m depth), particularly during juvenile life phases. These results suggest that these fish communities are sensitive to climate‐related changes in contemporaneous pelagic primary production in addition to the timing and magnitude of spring phytoplankton blooms.

Phase Shift in an Estuarine Finfish Community Associated with Warming Temperatures

AbstractFinfish abundance indices, produced from seasonal trawl survey data collected in Long Island Sound, were examined for changes in community composition related to the dynamics of water temperature from 1984 to 2008. In general, seasonal mean catch of species identified a priori as cold adapted significantly decreased while warm‐adapted and subtropical species significantly increased over the time series. Bottom water temperature also significantly increased. As a group, annual abundance of cold‐adapted species exhibited significant negative correlation with mean bottom water temperatures while warm‐adapted species, but not subtropical species, exhibited significant positive correlation. Multivariate analyses identified a shift in community structure producing two primary year‐groupings. Spring groupings were clearly delineated as 1984–1998 (cold period) and 1999–2008 (warm period). Autumn groupings were temporally discontinuous in the 1990s with group membership shifting between cold and warm periods, although the distal ends of the time series were clearly divided. These patterns aligned with deviations from the 1984 to 2008 mean bottom water temperature, indicating that this estuary is experiencing a relatively rapid shift consistent with a response to climate warming. The more distinct delineation of community structure in spring suggests that the lack of advantageous spring conditions was a more important factor in the decline of cold‐adapted species than increasingly stressful conditions in autumn.Received August 30, 2011; accepted April 7, 2012

Occurrence of finfish communities in trawl hauls of Atlantic Ocean in Badagry coast, Nigeria

Thirteen trawl hauls were conducted at depths ranging from 10 m – 100 m. Fifty six finfish families were observed, comprising ninety seven species from eighty two genera. Ten commercially important finfish families were identified out of which the Haemulidae had the highest number of occurrence and distribution with catch per unit area (CPUA) of 36.17 Kg/Km2. The Carangidae with CPUA of 22.09 Kg/Km2 was the lowest in abundance and distribution of the important finfish families. The total biomass estimate of finfishfrom the entire survey area under investigation was 440 tons (t). The middle stratum, S2 (30 m – 70 m) had the highest biomass followed by the land adjoining stratum, S1 (10 m -30 m) and the least stratum biomass wasobtained from the farthest stratum, S3 (70 m – 100 m). Fishing is optimized in the middle stratum, S2.

Impact of the Charleston Ocean Dredged Material Disposal Site on nearby hard bottom reef habitats

The deepening of shipping and entrance channels in Charleston Harbor (South Carolina, USA) was completed in April 2002 and placed an estimated 22 million cubic yards (mcy) of material in the offshore Charleston Ocean Dredged Material Disposal Site (ODMDS). To determine if sediments dispersed from the ODMDS were negatively affecting invertebrate and/or finfish communities at hard bottom reef areas around the disposal area, six study sites were established: three close to and downdrift of the ODMDS and three upcurrent and farther from the ODMDS. These sites were monitored biannually from 2000 to 2005 using diver surveys and annually using simultaneous underwater video tows and detailed sidescan-sonar. In general, the sediment characteristics of downdrift sites and reference sites changed similarly over time. Overall, the hard bottom reef areas and their associated communities showed little evidence of degradation resulting from the movement of sediments from the Charleston ODMDS during the study period.

Analyzing the tradeoffs among ecological and fishing effects on an example fish community: A multispecies (fisheries) production model

Species interactions such as predation or competition can have notable implications for fish population dynamics. Stock status and associated biological reference points can be misrepresented if these interactions are not considered. Here we present a multispecies, biomass production model (MS-PROD) developed by incorporating modifications to the Schaefer production model. The modifications explicitly emphasize a functional group approach, highlighting the effects of species interactions that include competition between species within a group, competition between groups, and predation. The mathematical formulation also includes constraints on carrying capacity for both the entire system and for individual groups. We applied the model as initialized to the Northeast U.S. Large Marine Ecosystem finfish community. We then executed simulations designed to explore the behavior of the model with respect to fishery exploitation and ecological interactions. Collectively, the results demonstrated the utility, and the need, for incorporating ecological effects into fisheries models.

Changes in finfish community structure associated with an offshore fishery closed area on the Scotian Shelf

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 240:249-265 (2002) - doi:10.3354/meps240249 Changes in finfish community structure associated with an offshore fishery closed area on the Scotian Shelf Jonathan A. D. Fisher1, Kenneth T. Frank2,* 1Department of Biology, Life Science Centre, Dalhousie University, 1355 Oxford Street, Halifax, Nova Scotia B3H 4J1, Canada 2Department of Fisheries and Oceans, Marine Fish Division, Bedford Institute of Oceanography, PO Box 1006, Dartmouth, Nova Scotia B2Y 4A2, Canada *Corresponding author. E-mail: frankk@mar.dfo-mpo.gc.ca ABSTRACT: In 1987 a large area (~13700 km2) associated with 2 offshore banks on the Scotian Shelf (Nova Scotia, Canada) was closed to commercial trawling for groundfish in order to protect the juvenile stages of haddock Melanogrammus aeglefinus from discarding. We assessed possible changes in the finfish community structure before and after the closure. Species abundance data collected annually since 1970 were subjected to multivariate analyses such as cluster analysis and a randomization/permutation test. Finfish community composition was significantly different after the implementation of the closure, and several species contributed to the post-closure difference including herring Clupea harengus, winter flounder Pseudopleuronectes americanus and redfish Sebastes sp., which showed dramatic increases in abundance. Haddock was the dominant species throughout the entire period. These findings suggest that several members of the finfish community benefited from the area closure. However, community structure in a reference area that has never been closed to fishing (Browns Bank) became more similar to the community structure in the closed area, contrary to our expectations. We provide support for the hypothesis that the dynamics of the Browns Bank area finfish community are coupled to the closed area through spillover based on several lines of inquiry, including positive relationships between abundance and area occupied of the dominant species and non-contemporaneous increases in species abundance between the closed area and the Browns Bank area with lags ranging from 1 to 3 yr. This study argues that establishment of fishery closures is likely to have positive benefits to the component species at both local and regional scales; however, the time-scale for such changes appears to be relatively long in comparison to tropical systems. KEY WORDS: Marine-protected area · MPA · Finfish community structure · Spillover · Marine conservation · Multivariate statistics · Biodiversity Full text in pdf format PreviousNextExport citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 240. Online publication date: September 12, 2002 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2002 Inter-Research.

Changes in piscivory associated with fishing induced changes to the finfish community on Georges Bank

There are many ecologically and commercially important piscivores in the Georges Bank fish community. There has been a noticeable shift in the abundance of these predators during the last four decades which is generally attributed to fishing pressure. Although many fish persist as piscivores in this system, not only has their relative abundance changed but their size composition has also changed. Both factors influence the total magnitude of piscivory by these fish. To ascertain the cascading effects of fishing on fish predation, we examined relative abundance, total stomach contents, diet composition, consumption rates, and total food consumption of fish for several species across the time period. The proportion of the diet comprised by fish for piscivores on Georges Bank has remained remarkably consistent. However, the composition of specific fish prey has changed across the time series. Total fish consumption generally tracked predator abundance, but two species demonstrated compensating consumption rates as larger size classes declined. Contrary to our initial hypothesis, total fish consumption by six major predators has remained generally constant despite changes in predator size, structure and abundance. One reason for constant systemic piscivory is the dominant piscivore in this ecosystem has shifted from cod to spiny dogfish. We assert that a major effect of intense fishing pressure is a shift in energy flow for marine ecosystems.

Ecological condition of the estuaries of the Atlantic and Gulf coasts of the United States

Monitoring the estuaries of the Atlantic and Gulf of Mexico coastlines of the United States from Cape Cod, Massachusetts, to Brownsville, Texas, was performed annually from 1990 through 1997 to assess ecological conditions on a regional basis for four biogeographic provinces. These province estimates--Virginian, Carolinian, West Indian, and Louisianian Provinces--are combined to provide an assessment of 87% of the estuarine area of the United States and 96% of the area of the Atlantic and Gulf coasts. Combining information over the six years of monitoring showed 34 +/- 4% of the Atlantic and Gulf estuarine sediments displayed poorer than expected biological conditions, based on benthic and finfish community conditions, and 21 +/- 4% of the area was characterized by low water clarity, the presence of marine debris/noxious odors, or elevated fish tissue contaminants.

The effect of fishing on the marine finfish biomass in the northwest Atlantic from the gulf of Maine to Cape Hatteras : BROWN B. E., J. A. BRENNAN, M. D. GROSSLEIN, E. G. HEYERDAHL and R. C. HENNEMUTH, 1976. Int. Commn NW Atlantic Fish. Res. Bull., 12: 49–68

Relationships between fishing eftort, total finfish community biomass, and yield are determined using data on finfish biomass measured by research vessel trawl surveys and commercial catch and effort statistics. Combined individual species stock assessments and the Schaefer (1954) equilibrium yield model are utilized to estimate potential yields. The fishing effort of different gear types are combined to provide a standardized index of fishing effort in terms of days fished as reported to the International Commission for the Northwest Atlantic Fisheries (lCNAF). A multiplicative learning function is applied as a correction factor to reported days fished of newly developing fisheries, i.e. those deployed in areas and on stocks not previously fished. This correction factor adjusts data of fleets entering a fishery to the level of efficiency achieved by the third year in the fishery. These analyses demonstrate a six-fold increase in fishing intensity, and a 55% decline in finfish abundance during the period 1961-72. Plots of yield versus standardized fishing effort indicate that fishing mortality since 1968 has exceeded that which would result in sustaining a maximum yield from the stocks under equilibrium conditions. The projected maximum sustainable yield (MSY) from Schaefer yield curves is 900,000 tons2 , while the sum of the MSY's from individual assessment studies is 1,300,000 tons. It is suggested that because of species interactions summing the MSY's from individual assessments may be an overestimate of the total MSY.