Kaitlin Hanak and James E. McKenna Jr. Changes in Observed Fish Community Structure Due to Immediate Replication of Beach Seine Haul Kaitlin Hanak and James E. McKenna Jr. Tunison Laboratory of Aquatic Science, U.S.G.S., Cortland, NY Abstract Two beach seine hauls were done in succession over the same area in the Oswegatchie watershed in an attempt to thoroughly sample the fish community. Out of the 101 sample sites and 202 seine hauls a total of 41,453 fish of 46 species were captured. There were notable differences in the composition of fish between the first and second replicates. The first haul captured a higher number of fish (p<0.01; mean of first haul=278, second haul=109). Certain fish species, such as Fathead Minnows (p<0.04) and Banded Killifish (p=0.05), were found in higher proportions in the first haul, while other species, including Pumpkinseed (p<0.01) and Central Mudminnow (p<0.04) were found in higher proportions in the second haul. Fish that fed in the water column were found in higher proportions in the first haul (p<0.01). Fusiform shaped fish were more likely to be found in the first haul (p<0.01), while laterally compressed fish were more likely to be found in the second haul (p<0.02). Ecological or behavioral traits may be responsible for the differences of species composition between replicates. Conducting two seine hauls over the same area may provide a more complete representation of an area’s fish community, but the cause of replicate differences needs more investigation. Figure 2. Comparison of species in proportion to total haul Results The 101 sites and 202 seine hauls yielded 41,453 fish of 46 species. The first haul yielded 29,764 fish, while 11,689 fish were captured in the second (Figure 1). The mean catch was 278 fish for the first haul and 109 for the second haul. More fish were captured in the first haul than in the second (p < 0.01) (Table 2.). The first haul also contained greater species richness (p < 0.01), with a mean of 5.66 for the first haul and 4.86 for the second. Diversity was similar between hauls, but there were on average 1.13 new species caught in the second haul. Certain types of fish were more likely to be found in either the first haul or the second haul (Figure 2). Fathead Minnow (p < 0.04) and Banded Killifish (p = 0.05) were found in higher proportions in the first haul. Pumpkinseed (p < 0.01) and Central Mudminnow (p < 0.04) were found in higher proportions in the second haul. The first haul also had higher proportions of fish that were fusiform in shaped (p < 0.01) and/or feed in the water column (p < 0.01). Fish that were laterally compressed were found in higher proportions in the second haul (p < 0.01). Generalist feeders appeared to be found in higher proportions in the second haul and the t-test was almost significant (p < 0.07). Figure 1. Relative Abundance of Species per Haul Introduction Seining is a commonly used method of sampling fish populations in shallow water. Seining takes minimal equipment, is fairly easy to complete, and is quantifiable because the volume of water filtered can easily be calculated. However, the efficiency of seining can be affected by a variety of factors and only a portion of the fish in the area will be retained. Factors intrinsic to the habitat such as bottom type, presence of snags or other obstacles, or water flow can affect seining efficiency (Allen et al. 1992). Also, fish often evade the seine (Bayley & Herendeen, 2000), and some species are more prone to capture than others (Lyons, 1986). It is important to take this into consideration when sampling fish populations. The method of seining affects the outcome and technique can maximize the gear efficiency. We conducted two seine hauls in succession over the same area in an attempt to more accurately sample the lotic fish communities of the Oswegatchie watershed. We expected a larger portion of the fish in the sampled area to be captured. Furthermore, the fish species that evaded the first seine haul were expected to be caught in the second seine haul in higher proportions. Thus, we expected that a double haul provides a more complete representation of the fish assemblage in the sample area. Species Body Shape Trophic Level Banded Killifish FF WC Black Crappie LC TC Blacknose Dace BI Blacknose Shiner Bluegill GF Bluntnose Minnow Brassy Minnow Brook Stickleback Brown Bullhead Central Mudminnow Channel Darter Common Carp Common Shiner Creek Chub Cutlips Minnow Eastern Sand Darter Eastern Silvery Minnow Emerald Shiner Fallfish Fantail Darter Fathead Minnow Finescale Dace Golden Shiner Goldfish Johnny Darter Largemouth Bass Logperch Longnose Dace Mimic Shiner Northern Pike Northern Redbellied Dace Pumpkinseed Rock Bass Rosyface Shiner Sand Shiner Silver Lamprey Silver Redhorse Smallmouth Bass Spotfin Shiner Spottail Shiner Tadpole Madtom Tesselated Darter Walleye White Sucker Yellow Bullhead Yellow Perch Paired T-test Results Mean Haul 1 Haul 2 DF T-value P-value Species Richness 5.66 4.86 96 3.6208 0.0005 Species Diversity 0.98 0.96 0.5706 0.5696 Total 278 109 100 3.1007 0.0025 Species Pumpkinseed 0.27 0.43 76 -3.1381 0.0024 Central Mudminnow 0.32 11 -2.3927 0.0357 Rock Bass 0.33 0.40 42 -1.2425 0.2209 Fathead Minnow 0.36 0.21 17 2.2301 0.0395 Banded Killifish 0.25 0.10 27 2.0147 0.0540 Rosyface Shiner 0.09 0.05 20 1.8670 0.0653 Brassy Minnow 0.24 0.17 13 1.9515 0.0729 Body Shape Guilds Flat Bodied Fish 0.72 0.84 -2.3838 0.0190 Round Bodied Fish 0.82 0.66 3.3662 0.0011 Trophic Guilds Water Column Feeder 0.15 2.6713 0.0088 Generalist Feeder 0.94 1.03 -1.8324 0.0699 Top Carnivore 0.30 0.8749 0.3837 Benthic Invert Feeder 0.14 0.11 0.9618 0.3385 Discussion There were significant differences between the composition of fish assemblages between replicate seine hauls. This has also been reported in a previous study in the St. Lawrence Valley (McKenna et al. 2012, 2013). The differences we observed were most likely due to the ecology (e.g., microhabitat and adaptations) of the fish and their behaviors in reaction to the seine. The species that were caught more often in the first haul were likely less adept at fleeing or were reluctant to leave their space. The species that were caught in the second haul in higher proportions may have evaded the net in the first haul but failed to do so during the second haul, possibly due to increased turbidity. There is also a possibility that benthic prey items disturbed by the first pass may have attracted fish that were not in the immediate area during the first run. Many of the same species collected by the first haul were also present in the second haul, although usually in lower abundance. Although it is clear there is a difference in the composition of the replicates, the cause of this difference requires more investigation. There is reasonable evidence showing an additional seine haul can change the composition of the sample and represent a wider variety of fish within the Oswegatchie River watershed. However, we do not know how well the sample reflects the actual community structure and whether or not similar outcomes would be achieved in different water bodies. Methods Fish populations were sampled in the Oswegatchie River main stem and tributary waters to examine the fish communities of the drainage system as part of the Fish Enhancement, Mitigation, and Research Fund (FEMRF) evaluation of threatened, endangered, and declining species of the St. Lawrence River and its tributaries. Both randomly selected sites and those likely to support rare or endangered species (based on model predictions) were sampled by seine for fish. Only seineable sites were sampled. All sites were ≤1.2 m deep, did not contain boulders, and did not have major protruding snags. A hybrid seine net 9.1 m wide and 1.2 m tall, with a 1/8” mesh bag and ¼” mesh wings was used (McKenna et al. 2013). Two people deployed the seine using ropes between the poles to ensure the seine opening was 4.6 m wide and the length of the haul was 9.1 m long to keep samples consistent. After the initial seine haul, fish were collected in a bucket with an aerator and an additional seine haul was then deployed over the same area in the opposite direction. Fish from both seine hauls were recorded and enumerated separately and released. All recorded data were entered and analyzed using MS Excel. Paired T-tests were used to determine if values from the first haul differed from values in the second haul. Both individual species that contributed strongly to differences in haul composition and species guilds (i.e., body shape and trophic group) (Table 1.) were evaluated for differences between hauls. Differences in species richness and diversity were also tested. Proportional data were subjected to an arcsine-square root transformation to compensate for the binomial distribution. Table 2. Paired T-test results. Species richness, species diversity and total were based on catch numbers. Other variables were based on proportions and were transformed before analysis. Significant results are bold, nearly significant results are italic. Table 1. Species grouping based on body shape (FF = fusiform, LC = laterally compressed) and trophic level (WC = water column, TC = top carnivore, GF = general feeder, BI = benthic invertivore) References Allen DM, Service SK, Ogburn-Matthews MV. 1992. Factors influencing the collection efficiency of estuarine fishes. Transactions of the American Fisheries Society. 121:234–244. Bayley PB, Herendeen RA. 2000. The efficiency of a seine net. Transactions of the American Fisheries Society. 129:901–923 Lyons J. 1986. Capture Efficiency of a Beach Seine for Seven Freshwater Fishes in a North-Temperate Lake. North American Journal of Fisheries Management. 6:288-289. McKenna Jr JE, Abbett R, Waldt E, David A, Snyder J. 2013. Hybrid seine for full fish community collections. Journal of Freshwater Ecology 28:1, pages 125-131. McKenna, Jr JE, David A, Johnson JH, Dittman DE. 2012. Evaluation of threatened, endangered, and declining species of the St. Lawrence River and its tributaries. Final report to the Fish Enhancement, Mitigation and Research Fund Projects # 2005-0129-010 and #2005- 0129-009. Cortland (NY): US Fish and Wildlife Service, Ecological Services Office.