Under what conditions do we expect spawning-season closures to be effective at protecting largemouth and smallmouth bass stocks?

Picture1Black basses such as largemouth bass and smallmouth bass support popular recreational fisheries across North America.  In addition to length limits and bag limits, bass stocks are often managed with seasonal closures during spawning, particularly in their northern regions.  Spawning season closures are viewed as important regulations for bass (Quinn 1993, 2002) because they are nest brooders, with the males guarding the eggs and fry until they become free swimming.  There is a wealth of literature demonstrating that a nest guarding male can be very aggressive and therefore more vulnerable to being caught by recreational anglers (e.g., Suski and Philip 2004).  When removed from the nest, the eggs are susceptible to predation by other fishes and the stress on the captured male can lead to nest abandonment even when released.  It is therefore believed that this disruption can lead to an overall reduction in the population level fecundity for that year and perhaps lead to reduced fish stocks (Suski et al. 2003).  Whether the protection of fecundity through spawning season closures is effective at protecting fish stocks depends on the strength and timing of density dependent compensation in juvenile survival.  Although currently there are no studies determining the timing of density dependent survival in black basses, a common hypothesis for many fish species is that density dependence occurs within the first year of life after hatching.  This is often referred to as recruitment compensation and is the basis for theories of surplus production that commercial fisheries regulations are often based on (Walters and Martell 2004).Picture2

If we adopt this theory of recruitment compensation for black basses, how would we expect seasonal closures to perform?  Or, more specifically, under what conditions would we expect seasonal closures to perform well for protecting black bass fish stock?  In the paper, “Exploring population-level effects of fishery closures during spawning: an example using largemouth bass” (Gwinn and Allen 2010) we investigated this question and found that the performance of seasonal closures relative to other forms of closures depended on the productivity and level of exploitation of the stock.  Seasonal closures performed best for low productive stocks, as you would expect in northern parts of their range, receiving uncommonly high levels of catch and release fishing effort.  On the other hand, when fishing effort was low or the productivity of the stock was high, spawning season closures had little effect on the stock.  These results support the common use of spawning season closures for bass in northern North America relative to southern North America; however, the levels of exploitation needed before spawning season closures are effective is uncommon (Allen et al. 2008).  This suggests that the intuitive conclusion that protecting fecundity equates to protecting the stock is not always true and may not be necessary for responsible management of many black bass fisheries.

References:

Allen, M.S., C.J. Walters, and R. Myers. 2008. Temporal trends in largemouth bass mortality, with fishery implications. North American Journal of Fisheries Management 28: 418-427.

Gwinn, D.C., and M.S. Allen. 2010. Exploring population-level effects of fishery closures during spawning: an example using largemouth bass. Transactions of the American Fisheries Society 139: 626-634.

Quinn, S. 1993. Bass seasons: conservation measure or needless regulation? Fisherman 18: 30-38.

Quinn, S. 2002. Status of seasonal restriction on black bass fisheries in Canada and the United States. Pages 455-465 in D.P. Philipp and M.S. Ridgway, editors. Black bass: ecology, conservation, and management. American Fisheries Society, Symposium 31, Bethesda, Maryland.

Suski, C.D., J.H. Svec, J.B. Ludden, F.J.S. Phelan, and D.P. Philipp. 2003. The effect of catch-and-release angling on parental care behavior of male smallmouth bass. Transactions of the American Fisheries Society 132: 210-218.

Suski, C.D., and D.P. Philipp. 2004. Factors affecting the vulnerability to angling of nesting male largemouth and smallmouth bass. Transactions of the American Fisheries Society 133: 1100-1106.

Walters, C.J., and S.J.D. Martell. 2004. Fisheries ecology and management. Princeton University Press, Princeton, New Jersey.

Advertisements

About dangwinn

I am a quantitative ecologist interested in patterns in biodiversity and natural resource management.
This entry was posted in fisheries management, recreational fisheries and tagged , , , , , , . Bookmark the permalink.

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s