Introduction: Smallmouth bass (SMB) presence in Miramichi Lake was reported to NB DNRE in late summer 2008. Fish and Wildlife Branch biologists confirmed their presence by successful capturing young-of-the-year (YOY) SMB in early fall. Since that time barriers have been installed to contain the SMB in Miramichi Lake. Surveys of the outlet stream and the Southwest Miramichi River near the outlet stream have failed to detect any SMB except in the upper 350 meters of the outlet stream which is effectively an extension of the lake. Any SMB encountered in this stream section have been removed by weekly backpack electrofishing.

Five year classes, ages 0+, 1+, 2+, 3+, and 4+, were found in the 64 SMB captured during extensive fishing in Miramichi Lake during 2009. Although spawning appears to have been successful for several years in succession, abundance remains low.

This field plan is a strategy to maintain containment while depleting the SMB in Miramichi Lake with the goal of eradication. Other important goals are to estimate the population size and age structure of SMB in Miramichi Lake and with this provide a measure of the effectiveness of the removal strategy at the end of each season.

A variety of fishing techniques will be employed to capture and remove SMB from the lake. It must be emphasized that this fishing will be intensive and bycatch of other fish species is unavoidable. As much as possible live release of bycatch will be practiced. Gear selections detailed in the methods below will be modified as needed during the field season to maximize the catch and removal of SMB from Miramichi Lake.

Boat Electrofishing: Other programs aimed at capturing SMB in lakes have found that boat electrofishing is the most effective method for capturing bass (Weidel et al 2007).  In addition the technique allows live release of non target species so impact is minimized.

SMB would be vulnerable to boat electrofishing from May when the lake water reaches temperatures above 10 degrees C and greater until fall when water temperatures drop below 10 degrees (Armour 1993). The electrofishing boat would be required from May until October when the water cools and SMB have moved to deep water.

A major effort should be placed on boat electrofishing from May until the end of June to target spawning fish and males guarding nests. This is the best opportunity to prevent / minimize successful reproduction of SMB by removing a large percentage of the spawning population.

We propose removing a target removal rate of 90% of SMB spawners during the May – June reproduction period for SMB.  Regardless of the removal rate the amount of boat electrofishing effort needs to be large and at least six sweeps of the littoral zone will likely be needed.

Boat Electrofishing at Night: Electrofishing catch rates for SMB have been found to be 2.1 to 4.1 X catch rates during daylight (Paragamian 1989). Nighttime operations are recommended to improve gear efficiency and increase the number of SMB removed per hour. The electrofishing boat must be equipped with lights to allow electrofishing after dark.

After spawning season: Boat electrofishing is likely going to remain the most effective method for capturing and removing SMB. The abundance will be much reduced and the objective should be to complete a sweep of the entire lake each week, targeting areas where SMB have been captured earlier in the season.

September-October: Typically this has been the time when boat electrofishing surveys were done on lakes as capture rates are highest at this time of year. Young-of-the-year SMB will be caught, if early efforts were insufficient to prevent successful reproduction.

Nest Location Verification and Destruction: All locations where SMB adults are captured will be recorded by GPS during boat electrofishing. Each of these sites will be visited during daylight hours when these potential nest sites are visually examined by snorkeling. Upon verification of an existing nest any eggs or larvae remaining will be removed by slurp gun. The snorkeling will also allow additional removal of adults (pole spear) and nest destruction.

Fyke nets will be deployed once water temperatures have reached 10 degrees C until fall when the water temperatures fall below 10 degrees and SMB are no longer catchable.

Initially, vents allowing smaller fish to escape will be installed to decrease the bycatch and target larger spawning adult SMB in spring. In June the escape vents will be removed but if bycatch is unmanageable then decisions will need to be made in the field as to how many nets w/o escape vents can be operated.

Fyke nets are fished in the same shallow water habitat where boat electrofishing is taking place. Information on the location of SMB from boat electrofishing will be used to place fyke nets in areas where SMB are found.

Gillnetting: Gillnets are the gear for targeting SMB in deeper (3 to 7 meters) part of Miramichi Lake. They can be deployed for the entire length of the field season since SMB move to deep water when water temperatures are below 10 degrees C but use deep lake waters in summer.

Gillnet fishing intensity will vary throughout the season. Initially effort will be high to remove as many adult SMB as possible before spawning begins in late May. Adult SMB will be moving from deep holes to shallow spawning sites and should be vulnerable to capture. Overnight sets will be used. However if bycatch is unmanageable gillnets sets could be restricted to daylight hours to decrease the bycatch (Honda and Fujita 2005). Upon arrival of adult gaspereau in late May or early June the gillnetting effort would be reduced to only the 4 and 5 inch mesh nets which would not retain gaspereau.

A commercial approach to fishing gillnets is recommended with the addition of one index gillnet set/day where all species are sorted and counted. Mesh sizes will be from 2 to 5 inches to target the 20 to 50 cm adult SMB in the lake

Angling: Angling will not be part of the program as abundance of SMB is too low for good angling success.

References:

Armour, CL. 1993. Evaluating temperature regimes for protection of smallmouth bass. US Fish and Wild Serv Resource Pub 191: 27 p.

Brousseau, CM., RG Randall, and MG Clark. 2005. Protocol for boat electrofishing in nearshore areas of the lower Great Lakes: transect and point survey methods for collecting fish and habitat data, 1988 to 2002. Can Man Rep Fish Aquat Sci 2702. 94 p.

Fujita, K, N Honda, T  Watanabe, and Y Matsushita 2007. Mesh size selectivity of gillnets for smallmouth bass. Tech Rep Nat Res Inst Fish Eng: 29, 55-61.

Gross, ML and AR Kapuscinski 1997. Reproductive success of smallmouth bass estimated and evaluated from family-specific DNA fingerprints. Ecology 78, 1424-1420.

Honda, N and K Fujita 2005. Selective fishing of smallmouth bass (Micropterus dolomieu) by soaking time of gillnets. Nippon Suisan Gakkaiski 71: 60-67.

Odenkirk, J and S Smith, 2005. Single- versus multiple-pass boat electrofishing for assessing Smallmouth Bass populations in Virginia Rivers. N Am J Fish Mgt 25: 717-724.

Paragamian, Vaughn L 1989. A comparison of day and night electrofishing: Size structure and catch per unit effort for smallmouth bass. N Am J Fish Mgt 9: 500-503.

Weidel, BC., DC. Josephson, and CE. Kraft, 2007. Littoral fish community responses to Smallmouth Bass removal from an Adirondak Lake. Trans Am Fish Soc 136: 778-789.

Zipkin, EF., PJ Sullivan, EG Cooch, CE Kraft, BJ Shuter, and BC Weidel, 2008. Overcompensatory response of a smallmouth bass (Micropterus dolomieu) population to harvest: release from competition? Can J Fish Aquat Sci 65: 2279-2292.