Multiple Gear Types Research Articles

A description of the nearshore fish communities in the Huron–Erie Corridor using multiple gear types

Great Lakes coastal wetlands provide a critical habitat for many fish species throughout their life cycles. Once home to one of the largest wetland complexes in the Great Lakes, coastal wetlands in the Huron–Erie Corridor (HEC) have decreased dramatically since the early 1900s. We characterized the nearshore fish communities at three different wetland complexes in the HEC using electrofishing, seines, and fyke nets. Species richness was highest in the Detroit River (63), followed by the St. Clair Delta (56), and Western Lake Erie (47). The nearshore fish communities in the Detroit River and St. Clair Delta consisted primarily of shiners, bluntnose minnow, centrarchids, and brook silverside, while the Western Lake Erie sites consisted of high proportions of non-native taxa including common carp, gizzard shad, goldfish, and white perch. Species richness estimates using individual-based rarefaction curves were higher when using electrofishing data compared to fyke nets or seine hauls at each wetland. Twelve fish species were captured exclusively during electrofishing assessments, while one species was captured exclusively in fyke nets, and none exclusively during seine hauls. Western Lake Erie wetlands were more indicative of degraded systems with lower species richness, lower proportion of turbidity intolerant species, and increased abundance of non-native taxa. This work highlights the importance of coastal wetlands in the HEC by capturing 69 different fish species utilizing these wetlands to fulfill life history requirements and provides insight when selecting gears to sample nearshore littoral areas.

Validation of mark-recapture population estimates for invasive common carp, Cyprinus carpio, in Lake Crescent, Tasmania

Summary A mark-recapture study based on the Petersen method was implemented in 1998 to estimate the abundance of the invasive common carp, Cyprinus carpio L., in Lake Crescent, Tasmania. Multiple gear types were employed to minimise capture bias, with multiple capture and recapture events providing an opportunity to compute and compare Petersen and Schnabel estimates. A single Petersen estimate on recapture data and two Schnabel estimates – one each on mark (forward-Schnabel estimate) and recapture (reverse-Schnabel estimate) data – were conducted. An independent long-term double tag study facilitated estimation of the annual natural mortality. Subsequent fish-down of the population suggests that, in all likelihood, the carp have been eradicated from the lake, providing an unprecedented opportunity to verify the forward population estimates carried out in 1998. Results suggest that all three estimates were close to the true population size, with the reverse-Schnabel estimate being the most accurate and within 1% of the true population in this relatively large lake (2365 ha). Greater accuracy of the reverse-Schnabel approach can be attributed to either minimised fish behavioural (i.e. gear susceptibility or avoidance) or computational bias associated with the forward- Schnabel and Petersen approaches, respectively. While the original estimates served as a guide in eradication of carp from the lake, the ultimate validation provides a reliable framework for abundance estimation of this invasive fish in relatively large water bodies elsewhere.

Improving social acceptability of marine protected area networks: A method for estimating opportunity costs to multiple gear types in both fished and currently unfished areas

We present a novel method for calculating the opportunity costs to fishers from their displacement by the establishment of marine protected areas (MPAs). We used a fishing community in Kubulau District, Fiji to demonstrate this method. We modelled opportunity costs as a function of food fish abundance and probability of catch, based on gear type and market value of species. Count models (including Poisson, negative binomial and two zero-inflated models) were used to predict spatial abundance of preferred target fish species and were validated against field surveys. A profit model was used to investigate the effect of restricted access to transport on costs to fishers. Spatial distributions of fish within the three most frequently sighted food fish families (Acanthuridae, Lutjanidae, Scaridae) varied, with greatest densities of Lutjanidae and Acanthuridae on barrier forereefs and greatest densities of Scaridae on submerged reefs. Modelled opportunity cost indicated that highest costs to fishers arise from restricting access to the barrier forereefs. We included our opportunity cost model in Marxan, a decision support tool used for MPA design, to examine potential MPA configurations for Kubulau District, Fiji Islands. We identified optimum areas for protection in Kubulau with: (a) the current MPA network locked in place; and (b) a clean-slate approach. Our method of modelling opportunity cost gives an unbiased estimate for multiple gear types in a marine environment and can be applied to other regions using existing species data.

TAC assessment for single species and multiple gear fisheries with an application to the Korean hairtail fishery

This paper describes a Total Allowable Catch assessment model for a single species and multiple gear types as an improvement on TAC assessment based on a single species and a single gear type. A case study is included for a hairtail species caught mainly by the Korean pair trawl and large otter trawl gears. We use a surplus production model based on the exponential growth model to estimate biological reference points. Fishing effort for the two gears is standardized and used in a general linear model. The Fox bioeconomic model is then used to estimate economic reference points. In the Korean hairtail fishery, the TAC assessment model for a single species and multiple gear types yielded values for each reference point that were more conservative.

Sampling a Littoral Fish Assemblage: Comparison of Small‐Mesh Fyke Netting and Boat Electrofishing

AbstractWe compared small‐mesh (4‐mm) fyke netting and boat electrofishing for sampling a littoral fish assemblage in Muskegon Lake, Michigan. We hypothesized that fyke netting selects for small‐bodied fishes and electrofishing selects for large‐bodied fishes. Three sites were sampled during May (2004 and 2005), July (2005 only), and September (2004 and 2005). We found that the species composition of captured fish differed considerably between fyke netting and electrofishing based on nonmetric multidimensional scaling (NMDS). Species strongly associated with fyke netting (based on NMDS and relative abundance) included the brook silverside Labidesthes sicculus, banded killifish Fundulus diaphanus, round goby Neogobius melanostomus, mimic shiner Notropis volucellus, and bluntnose minnow Pimephales notatus, whereas species associated with electrofishing included the Chinook salmon Oncorhynchus tshawytscha, catostomids (Moxostoma spp. and Catostomus spp.), freshwater drum Aplodinotus grunniens, walleye Sander vitreus, gizzard shad Dorosoma cepedianum, and common carp Cyprinus carpio. The total length of fish captured by electrofishing was 12.8 cm (95% confidence interval = 5.5–17.2 cm) greater than that of fish captured by fyke netting. Size selectivity of the gears contributed to differences in species composition of the fish captured, supporting our initial hypothesis. Thus, small‐mesh fyke nets and boat electrofishers provided complementary information on a littoral fish assemblage. Our results support use of multiple gear types in monitoring and research surveys of fish assemblages.

Fish assemblages of perennial floodplain ponds of the Sacramento River, California (USA), with implications for the conservation of native fishes

AbstractTo assess the likelihood of enhancing native fish populations by means of floodplain restoration projects, habitat characteristics and fish assemblages of seven perennial floodplain ponds in Yolo Bypass, the primary floodplain of the Sacramento River, California (USA), were examined during summer 2001. Although all ponds were eutrophic, based upon high chlorophyll a or dissolved nutrient concentrations, relatively large shallow ponds generally exhibited higher specific conductivity and dissolved phosphorus concentrations than small deep ponds, which exhibited greater water transparency and total dissolved nitrogen concentrations. Using multiple gear types, 13 688 fishes comprising 23 species were collected. All ponds were dominated by alien fishes; only three native species contributing <1% of the total number of individuals and <3% of overall biomass were captured. Fish assemblage structure varied among ponds, notably between engineered vs. natural ponds, and was related to specific conductance, total dissolved solids and water transparency.

Development of Tagging Techniques for Monitoring Fish Populations at Texas Artificial Reefs

Texas Parks and Wildlife Department (TPWD) has used a broad range of methodologies to monitor the social, economic, and biological impacts of artificial reefs in the Gulf of Mexico. Social and economic issues have been addressed through charter boat and diver mail-in questionnaire surveys and on-site creel surveys. Biological issues have been investigated through hook and line tagging, diver-based visual transects, and video traps. Assessments of hydroacoustic and remotely operated vehicle (ROV) biological survey techniques are also planned for deepwater reef sites. There is also a need to develop inexpensive biological monitoring methods to track target fish populations such as red snapper over time at specific reef sites. The Department has been investigating the use of collapsible traps to tag fish underwater as a potential long-term monitoring tool for assessing reef fish populations. The cost effectiveness and efficiency of this gear type was compared to hook and line capture techniques. During the initial effort, 223 red snapper were tagged underwater by divers after capture by three collapsible traps, and 291 red snapper were tagged on the surface by anglers after capture by hook and line techniques. The collapsible traps appeared to be more size selective for smaller sized red snapper than hook and line techniques. Fish tagged underwater had a higher recapture rate of 25.45 percent compared to the 11.89 percent recapture rate for fish caught and tagged on the surface. Although three recapture periods were used to evaluate tag return data, our findings suggest that future efforts directed at monitoring artificial reef fish populations should use multiple gear types with equal effort applied to account for size-selective capture patterns and logistical constraints.

Yield estimates, catch, effort and fishery potential of the reef flat in Cape Bolinao, Philippines

Summary Catch, fishing effort and yield estimates of the Cape Bolinao reef flat fishery in Lingayen Gulf, Philippines are provided, based on data collected from May 1987 to April 1988. The dynamics of the dominant species, the rabbitfish Siganus fuscescens, suggest that such fisheries are capable of maintaining a high production in site of heavy fish in pressure. However, yield comparisons with those of other reef fisgeries in the Indo-Pacific region, along with characteristics of the catch and the use of multiple gear types, suggest that current extraction rates should not be increased.

Management of the 4WX Atlantic Herring (Clupea harengus) Fishery: An Evaluation of Recent Events

The Atlantic herring (Clupea harengus) fishery of the Scotian Shelf and Bay of Fundy regions of Canada (NAFO Divisions 4W and 4X) is pursued with multiple gear types including traps, gill nets and purse seines, which have evolved in importance over time with changing market emphasis. It was one of the first commercial fisheries to be regulated by limited entry (since 1970), and in 1972 it was the first to come under nationally allocated annual total allowable catch (TAC) limits. In 1976 an individual vessel quota scheme for purse seiners was established and operated jointly by the regulator and the harvesting sector. That initiative formed the basis of the 1983 10-Year Management Plan for 4WX herring that is reviewed and evaluated in this paper. The Plan, while not expressly achieving its original goals, and not fully realizing the implicit benefits of an individual transferable quota (ITQ) system, has contributed to the continuation of consensus management of this, the only large Atlantic herring fishery which has not suffered a major collapse. The development of successful management plans in the future must deal explicitly with ongoing problems of unstable markets for herring products and under-reporting of catches.

Finfish Utilization of Man-Initiated and Adjacent Natural Creeks of South Creek Estuary, North Carolina Using Multiple Gear Types

Three gear types were used to collect finfish species from several tributaries of the South Creek estuary near Aurora, North Carolina, to ascertain whether a man-initiated marsh and creek system resembled adjacent natural areas in finfish species composition and abundance. Project Area II was the man-initiated area constructed in 1983 as up-front mitigation by North Carolina Phosphate Corporation prior to its anticipated mining in the headwaters of nearby natural wetlands. Two creeks served as controls throughout the study: Drinkwater Creek and Jacks Creek. Otter trawls were used monthly from July 1984 through December 1988. Wegener rings were used in April, July, and October from 1984 through 1987. An experimental gill net was used monthly from June 1984 through 1985. A total of 48 finfish species was captured during the study; only 14 species (29.2%) were common among gear types. The species collected were mud sunfish, blueback herring, alewife American shad, striped anchovy, bay anchovy, inland silverside, American eel, silver perch, Atlantic menhaden, crevalle jack, common carp, spotted seatrout, weakfish, sheepshead minnow, gizzard shad, ladyfish, chain pickerel, banded killifish, mummichog, striped killifish, rainwater killifish, mosquitofish, naked goby, green goby, white catfish, brown bull-head, pinfish, longnose gar, green sunfish, pumpkinseed, bluegill, redear sunfish, spot, Atlantic croaker, largemouth bass, white perch, striped bass, striped mullet, white mullet, golden shiner, summer flounder, southern flounder, yellow perch, bluefish, Atlantic needlefish, hogchoker, andTilapia species. Abundance of finfish species was a function of gear type. Bay anchovy and spot represented about 85% of all fish in trawl samples. The remainder was comprised of 27 other species. In Wegener rings, five species—bay anchovy, menhaden, rainwater killifish, spot, and inland silverside—each represented over 10% of all fish collected. Croaker and striped mullet each comprised more than 5% of all fish collected in Wegener rings, but were present in substantial numbers only in 1985. Based on trawl samples, the total number of finfish collected from Project Area II during the period 1984–1988 was statistically similar to those collected from the control creeks; Wegener ring data analysis indicated significantly greater catches in Project Area II compared to the control creeks. Bay anchovy catches were not significantly different among the three creeks by either trawl or Wegener ring. The same result was true for Atlantic menhaden and southern flounder. The abundance of spot in trawl samples from Project Area II was significantly greater than for the control creeks; abundance in ring samples from Project Area II was statistically similar to Jacks Creek, but significantly higher than Drinkwater Creek. The number of Atlantic croaker in Project Area II trawl samples was significantly lower than for the cotnrol creeks. Wegener rings did not sample croaker effectively.

Inter-Annual Distributions of Larval and Pelagic Juvenile Cod (Gadus morhua) in Southwestern Nova Scotia determined with two Different Gear Types

Ichthyoplankton surveys conducted during 1979 on the Scotian Shelf have shown coincident egg and larval distributions for cod (Gadus morhua) and other related groundfish species. These data have been used by other investigators to support the larval retention hypothesis, in spite of three limitations: the exclusive use of a single type of small sampling gear, limited sampling landward of the 50-m isobath, and analysis of data collected in a single year. During May of 1985, 1986, and 1987 two gear types were used, from the shelf to coastal waters in southwestern Nova Scotia to assess the horizontal distributions of larval and pelagic juvenile cod. Tucker trawl collections made in each year revealed a cohort of cod [Formula: see text] that was not evident in the smaller gear, which effectively sampled cod larvae < 10 mm. During 1985 and 1986, when both larvae and juveniles were abundant, their distributions coincided. The mixture of sizes of cod from 3–45 mm reduced the importance of using multiple gear types. The interannual location of young cod shifted markedly between the nearshore and offshore demonstrating that a single year of sampling effort is inadequate to assess their distribution. Nearshore sampling revealed high densities of young cod as much as three-fold greater than offshore. The inshore waters may serve as a nursery area for young cod originating from offshore spawning sites. Our results confirm the existence of two important sampling limitations of previous cod ichthyoplankton surveys that reduce their utility as empirical support for the retention hypothesis.