Bunker fish are marine organisms that play a significant role in coastal ecosystems. Understanding their characteristics and behaviors helps illuminate their contribution to ocean health. These fish are also known by other names and impact many other species.
Defining Bunker Fish
Bunker fish are commonly recognized as Atlantic menhaden, scientifically classified as Brevoortia tyrannus, belonging to the herring family (Clupeidae). They are also known by various regional names such as mossbunker, pogy, or fatback. These fish are relatively small, typically reaching lengths of up to 15 inches and weighing around one pound when fully grown.
Their physical appearance features a silvery body, sometimes with a bluish-green or bluish-brown hue. A prominent black spot is located behind their gill opening, often followed by smaller spots arranged in horizontal rows along their sides. Menhaden have a moderately compressed body, a projecting lower jaw, and a deeply forked tail fin.
Where Bunker Fish Live and Thrive
Bunker fish inhabit coastal and estuarine waters, extending along the Atlantic seaboard from Nova Scotia in Canada down to northern Florida. They are found in all salinities of bays and estuaries, including the Chesapeake Bay. These fish are pelagic, meaning they live in the open water column, and are known for forming large, dense schools that swim close to the surface.
Their movements are influenced by seasonal changes and migration. During the warmer months, from spring through fall, menhaden are abundant in nearshore waters, with older and larger fish found further north. As temperatures drop in late fall and early winter, they migrate southward to deeper offshore waters, particularly off the North Carolina capes, where they overwinter. Juvenile menhaden spend their first year developing in estuaries, which serve as important nursery areas, before joining the adult schools.
Their Role in the Marine Ecosystem
Bunker fish are filter feeders, playing a significant role in water quality by consuming microscopic organisms. They primarily feed on phytoplankton and zooplankton, straining these tiny plants and animals from the water column through specialized gill rakers. This filter-feeding activity helps to clarify water and can contribute to mitigating harmful algal blooms.
Beyond their role as natural water purifiers, menhaden are a crucial link in the marine food web, serving as a primary food source for many marine predators. They are a nutrient-rich forage fish, providing sustenance for larger fish such as striped bass, bluefish, tuna, and sharks. Marine mammals like dolphins and humpback whales also rely on menhaden as a food source. Predatory birds, including ospreys and eagles, depend on these oily fish for their diet.
Bunker Fish and Human Activities
Humans have historically interacted with bunker fish, dating back to early colonial times when they were used as fertilizer for crops. Today, menhaden support one of the largest commercial fisheries by volume along the Atlantic Coast of the United States. This commercial activity primarily involves two types of fisheries: the reduction fishery and the bait fishery.
The reduction fishery processes whole menhaden into fishmeal, fish oil, and fish solubles, which are used in animal feed, aquaculture, and human dietary supplements due to their high omega-3 fatty acid content. The bait fishery harvests menhaden for use by both commercial and recreational fishermen, particularly for baiting traps for blue crabs and lobsters, and as chum for game fish. The primary method for catching menhaden in these large-scale operations is purse seining, a highly effective technique with minimal habitat impact. Management efforts utilize ecological reference points to balance harvest levels with the needs of the ecosystem, considering menhaden’s role as prey for other species.