Human Impacts on Bass

Prepared by Aaron Zolderdo, PhD student in Dr. Steven Cooke’s laboratory at Carleton University (

There are many diverse and complex challenges facing freshwater fish communities in Ontario. These issues are often wide-ranging and can vary greatly between water bodies. The root cause of many of these issues stems from human resource use.

The largemouth and smallmouth bass, collectively referred to as ‘black bass’, are two prominent species that have been subjected to intensive fisheries pressure throughout most of their native range, including within Big Rideau Lake and the connecting Rideau Lakes and Canal system. Both black bass species have been the focus of resource use coupled with rigorous management interventions since the late 19th century, largely due to their popularity in recreational fisheries. Today most bass are released, but historically, harvest rates were higher. 

Aside from fisheries interactions, habitat alteration and degradation is another contributing factor that can influence black bass populations. Quality habitat is vital to promote stable and healthy populations.

Recreational Fisheries

Recreational angling for black bass has been in effect since the mid 1800’s and continues into the present day. Historically, recreational angling was predominantly a catch-and-keep (C&K) fishery, where almost all black bass captured by anglers were harvested. C&K practices put considerable strain on black bass populations leading to significant declines in population numbers, and consequently availability and catchability. In extreme cases, population-level crashes occurred as a result of excessive harvesting and poor resource management. As a result, multiple stocking programs were implemented (especially in the USA), as early as 1873, to help alleviate angling pressure and increase population yields, but these have met with limited success.

Aside from population declines, C&K practices have left a legacy impact on the biology and ecology of bass populations through the selective harvesting of ‘vulnerable fish’; a phenomenon known as fisheries-induced evolution. The advent of catch-and-release (C&R) as a viable, and desirable, fisheries practice did not come about until the 1970’s. C&R for bass was initially conceived and implemented by the Bass Anglers Sportsman Society (B.A.S.S), which is a competitive sport fishing club operating throughout North America. C&R practices were slow to be adopted throughout the recreational angling community; in fact, C&R angling was not common practice until the 1990’s in Ontario. However currently C&R angling for black bass is the most common practice throughout the province, with C&R rates being greater than 90% in most water bodies. C&R practices have greatly benefited black bass as populations are more stable, healthy, and genetically diverse.

However, C&R is not completely harmless. Physiological stress, injury, and post-release mortality can occur. Most often, mortality occurs from ‘foul’ or ‘deep’ hooking of bass, where the hook of the lure is lodged within the stomach, gullet, gills, or eyes. Hooking in these areas can cause bleeding, infection, and/or interfere with day-to-day life (e.g., foraging abilities). Furthermore, deeper hooked fish require more handling time by the angler to remove the lure, which equates to longer air exposure (i.e., suffocation). In addition, excessive handling of captured fish can result in scale and ‘mucus membrane’ loss, which are essential components for immune defense and swimming performance. Angling duration (i.e., fight time) and water temperatures are also key factors influencing the fish’s physiological condition, as well as post-release survival. Prolonged fight times can induce excessive aerobic and anaerobic activity in a bass, which can deplete energy stores, reduce post-release predator avoidance abilities, and disrupt normal physiological processes - all of which can lead to reduced fitness and/or survival. However, most of these issues are under the direct influence of the angler such that if they adopt conservation-oriented behaviors injury, stress and mortality can be minimized.  Indeed, recreational fishing is an important component of the Canadian culture, economy, and identity – arguably more so than hockey given that participation rates for recreational angling are greater than for hockey!

Competitive angling, in the form of fishing tournaments, is an area of growing concern due to its rising popularity and prevalence. Since its inception in Texas during the mid-1950’s, the concept and practice of competitive angling has grown throughout North America, with estimates of over 22,000 fishing tournaments targeting black bass as determined by a survey conducted in 2000. In Ontario alone, a 2009 survey documented over 481 tournament events targeting black bass, with multiple tournaments being held on Big Rideau Lake and throughout the Rideau Lakes system every year.

During competitive tournament angling events multiple fish are often confined to livewells for extended periods of time on the same day as being caught. While confined to livewells, fish can quickly face poor water quality including increased ammonia and dissolved carbon dioxide, and decreased dissolved oxygen, resulting in hypoxia and physiological disturbance (e.g., stress and ion imbalance). This situation can be exacerbated by increased fish densities and prolonged confinement. Furthermore, fish are often ‘sloshed’ around by wave action and transportation, which can damage tissues (especially mouth parts and fins) and remove scales and mucus.

Another issue associated with competitive angling events is the translocation of fish from where they were initially captured, to where they are processed (i.e., the weigh-in station) and subsequently released. This relocation can cause ‘stacking’ of black bass in the release area and therefor potentially making them more vulnerable to angling exploitation. There are also concerns important to recognize for released bass managing (or not) to move back to their original home area and/or to locate new and suitable habitat as is required for a healthful and productive life.

Habitat Alteration

To date, there has been significant development in the protection and conservation of natural habitats within Ontario waterways. In addition, there are many rules and regulations that are imposed on human land use activities, which prohibit alterations that impair the natural form and function of aquatic environments. However, many land use activities still challenge aquatic environments.

For instance, human population growth and development (e.g., urbanization), agricultural activities, dam or canal construction, seasonal water-level drawdown and shoreline development are all factors that can disrupt and/or degrade habitat form and function. Specifically, these land use activities can significantly increase siltation and turbidity in aquatic environments. Black bass are visual predators that prefer non-turbid habitats. Increased turbidity can negatively impact foraging abilities, leading to habitat abandonment. Furthermore, increased siltation can cover vital spawning habitat, reducing offspring survival and development; which can negatively impact reproductive success. Bass are also structure-oriented fish – they love to hang out under logs, in vegetation, and behind stumps.  Efforts to clear areas for beaches can strip water bodies of the habitats bass need to thrive.  If vital habitat is degraded or destroyed then population level impacts can occur. 

Management and Conservation of black bass in Big Rideau Lake

Black bass are among the most intensively managed of fish species in the world. 

For example, generally speaking in Ontario, all persons engaging in recreational angling, except for those very young and over 65 years of age, regardless of targeted fish species, must purchase a fishing license from the Ontario Ministry of Natural Resources. There are two types of licenses available including ‘sport’ and ‘conservation’ which allow for differential catch-and-harvest quantities. This licensing system establishes set ‘bag limits’ for all fish species found in Big Rideau Lake, and the purchasing of a license allows individuals to actively catch-and-harvest/release fish. Also, special permits are available to enable tournament fishing operations to hold bass alive for a period of time so as to enable competitive weigh-ins and then for the fish to be released.  

There are also designated ‘closed seasons’ for many fish species, including both black bass species. Closed seasons prohibit recreational and/or commercial targeting of a specific species. If incidental capture of a protected fish during a closed season occurs, it must be released as quickly as possible (e.g., holding said fish for a photograph is illegal as the fish was not release as quickly as possible). The closed season for both black bass species in Big Rideau Lake generally extends from December 15 through to the third Saturday in June. However, it is considered good practice to routinely check regulations and best handling practices to ensure compliance with laws.

Lastly, Big Rideau Lake has several fish sanctuaries that totally prohibit angling within their boundaries 365 days a year. These protected areas are a management strategy that is somewhat unique to the Rideau Lakes system, and there are also several other year-round sanctuaries within neighboring lakes (e.g., Opinicon Lake, Newboro Lake, and Sand Lake). These fish sanctuaries were establish in the 1930’s – 1940’s in an effort to protect mainly largemouth bass from fisheries exploitation. Prior to the establishment of the sanctuaries, the largemouth bass population was under heavy exploitation, and resource managers at the time were concerned about potential stock collapse. As such, multiple sanctuaries were created to provide an unexploited ‘source’ population which could provide new recruits to the heavily exploited main lake populations. These sanctuaries remain intact today and support diverse fish populations. 

References and suggested further readings: 

Cooke, S., & Philipp, D. P. (Eds.). (2009). Centrarchid fishes: diversity, biology and conservation. John Wiley & Sons.

Philipp, D. P., & Ridgway, M. S. (2002). Black bass: ecology, conservation, and management. In American Fisheries Society, Symposium (Vol. 31). Bethesda Maryland.

Siepker, M. J., Ostrand, K. G., Cooke, S. J., Philipp, D. P., & Wahl, D. H. (2007). A review of the effects of catch‐and‐release angling on black bass, Micropterus spp.: implications for conservation and management of populations. Fisheries Management and Ecology, 14(2), 91-101.

Fisheries Management Plan (accompanied by Background Information) for Fisheries Management Zone 18.  February 2016.  Ontario Ministry of Natural Resources and Forestry.

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