Photo by Ryan Hagerty, USFWS.

February 1, 2023

Species Recovery Strategy for the State-threatened Mottled Sculpin

A tiny black and tan fish rests on the bottom of a gravel stream-bed beside a large rock.
Photo by Ryan Hagerty, USFWS.

Darting among crevices of rocks at the bottom of clear streams is a well-camouflaged fish with a preposterously oversized head. The mottled sculpin is a rarely seen fish inhabiting small streams of the Rock River, Fox River and Vermilion River (of the Wabash River) basins. This species can grow to 6 inches and consumes primarily aquatic insect larvae. They prefer areas of flowing water with large substrates (e.g., cobble, logs) where their prey is abundant. Mottled sculpin are indicative of streams with little sedimentation, moderately cool temperatures, and stable flow – characteristics that are rare in Illinois.

Mottled sculpin is a state-threatened species, meaning it is at risk of becoming endangered, and as such is protected under the Illinois Endangered Species Act. It is considered vulnerable to extinction due largely to its shrinking range and relatively high number and intensity of threats to its persistence. Mottled sculpin once were common in Lake Michigan, but now are considered extirpated from the Illinois portion of the Lake likely due to being outcompeted by the exotic fish round goby. In other parts of its range mottled sculpin habitats are being degraded by agricultural activities or by rapid urbanization. The species also is sensitive to the effects of climate change, like higher temperatures and reduced summer stream flows.

A small rocky stream flows through a lush green forest.
A Cook County stream that typifies the characteristics of streams where mottled sculpin might be found. Photo by Brian Metzke.

In Illinois, the continued persistence of mottled sculpins in the wild is in jeopardy, so how do the Illinois Department of Natural Resources (IDNR) and its conservation partners approach to management of its conservation status? IDNR has developed a conservation management strategy, called species recovery, for evaluating a species’ status, identifying conservation actions to maintain or enhance that status, and prioritizing resources to support those actions. Species recovery is a recursive approach to deliberately and strategically engaging in species management that enhances or maintains wildlife and plant populations in Illinois. Although Species of Greatest Conservation Need often are the focus of species recovery efforts, conservation management of any species or population may benefit from the principles of IDNR’s species recovery process.

The IDNR species recovery process occurs in three phases. First, in the species status assessment phase a contemporary evaluation of the species distribution, abundance and population viability is developed. This assessment provides context for engaging in conservation actions and a benchmark from which to monitor the efficacy of those actions. Phase two of the species recovery process identifies and prioritizes conservation actions that alleviate stressors, threats and information gaps. This action planning phase sets objectives and identifies resources required to enact conservation actions and culminates in appropriation of resources. Conservation actions are implemented in the third phase of the species recovery process. Actions may be stewardship, protection, research, monitoring, or education and outreach activities. As actions are implemented and the focal species’ status is reassessed the three-phase cycle continues with revisions of objectives and actions as is necessitated.

Development of the species recovery process framework continues, yet several species management milestones have been completed. Species status assessment standards and guidelines and 27 species assessments for state-endangered species have been published. Guidelines for conservation action planning have been implemented and conservation plans for four species have been drafted and will be used to allocate resources towards species management in 2023. Species-specific teams of scientists and agency staff have met to coordinate efforts, produce robust conservation plans, and will begin implementing actions in 2023. IDNR has developed a website to describe the species recovery framework, publish documents, and communicate successes.

A researcher holds up a small brown and tan fish in his hand. In the background is a stream in a lush green woodland.
Brian Metzke holding a mottled sculpin. Photo by Brian Metzke.

The recovery process is well-suited for identifying and implementing a framework for conservation of mottled sculpin and achieving the objectives of halting the species’ decline and maintaining its viability in all four of the basins in which it occurs. IDNR and its conservation partners have engaged in conservation management of mottled sculpin through the species recovery process. The mottled sculpin species status assessment (phase one) indicates the species’ distribution and abundance has declined, but that its conservation status is stable. Actions identified to improve or maintain the status of mottled sculpin (phase two) include studies to elucidate life history and ecological patterns and processes, fully utilize existing regulatory protection mechanisms to minimize harm to the species, and develop a translocation plan to assist recolonization of restored habitats. These actions support the conservation objectives of filling knowledge gaps and maintaining viable populations in each of the four watersheds in which it is extant.

Successful conservation of imperiled species depends, in part, on focused objectives, efficient allocation of resources, and partnerships. IDNR has developed its species recovery process to guide conservation actions and improve likelihood of successfully achieving conservation goals.

Brian Metzke is the State Aquatic Ecologist for the Illinois Department of Natural Resources. His work focuses on conservation of imperiled aquatic life and their habitats, characterizing streams and their biota, and community ecology of fish and freshwater mussels. Brian is the former president of the Illinois Chapter of the American Fisheries Society and the lead author of An Atlas of Illinois Fishes.

Isabella Newingham is the new State Wildlife Action Plan and Aquatic Ecology GPSI intern at the Illinois Department of Natural Resources. She graduated with a bachelor’s degree in Biology from Millikin University in 2020. She spent the year following graduation teaching at a local high school before starting at the University of Illinois Springfield to complete a master’s degree in Environmental Sciences with a concentration in Sustainable Development and Policy. While at Millikin University she completed research to observe behavioral responses in millipedes.

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