Stress on Black bass

Type: Nontidal
Region: Eastern
Location:

Adult bass have become increasingly rare in our surveys in the Choptank River. The decline in the number of adults is causing a decline in the number of offspring produced each year. The silt loads and lack of stable water with structure in the Choptank River also helps limit juvenile production. In order to help provide structure in silty, but stable water habitats, nest boxes were built by MDNR staff and volunteers from the Maryland Bass Federation Nation. These nest boxes are square boxes lined with either a layer of cobble or a spawning mat. To determine if largemouth bass use the nest boxes during the spawning season, boxes of each type will be placed within hatchery ponds at Cedarville and Unicorn. Largemouth bass will be observed daily to determine if males are utilizing the nest boxes. Some boxes will be placed in the Choptank River to determine if they�ll withstand the tides and current. If males use the boxes and they hold up in the Choptank River, then more will be used next year in the Choptank River to help provide structured habitats in areas of the river where structure is lacking.

The black bass fishery in tidal waters of Maryland has been open year-round for more than 50 years. During spring, anglers enjoy catching male black bass, which seem to fight more when guarding their nests. However, the stress of angling and the movement of males to other locations can leave their offspring defenseless and vulnerable to predators. The impact of nest abandonment by males on the population has not been well-established or studied in North America. The current assessments of populations in two heavily fished areas, the upper Bay and the Potomac River, indicate high juvenile production. None-the-less, some anglers have increasingly asked for a catch-and-release season during the spring spawning season. Because both catch-and-release angling and removal of fish from nests leave fry vulnerable to predators, sanctuaries (or off-limits zones during the spawning season) were established in 2001 in two streams of the Potomac River. These areas are non-fishing zones from 1 March � 15 June and are restricted from boaters. They were established in Nanjemoy River (area = 0.34 km2) and Chicamuxen Creek (0.11 km2). The Gumtree Cove Sanctuary in the Nanjemoy River is about 3 times the size of Chicamuxen Sanctuary.

We are currently assessing the Chicamuxen Sanctuary by tracking bass that were tagged using radiotags and surveying the sanctuaries. In 2011, we will also assess the Gumtree Cove Sanctuary in the Nanjemoy River. We will determine if males prefer to build nests in the sanctuaries and if sanctuaries offer quality habitat. Our goal is to effectively protect spawning habitat for largemouth bass, while minimizing potential negative impacts to catch-and-release anglers.

Photos by Tim Groves and Joe Love