In my experience the question of whether or not fish populations are impacted by "earlier spring" depends, in part, on their behavior ie., migratory or sedentary. In general, sedentary species should experience less impacts because their entire ecosystem (i.e., a pond or a lake) is changing as a unit - ie., earlier spawn and early hatch date of fish eggs is matched by earlier timing of the spring plankton bloom so events are not desynchronized. For migratory species you encounter greater potential negative consequences. For example, Fraser River sockeye salmon are entering freshwater and reaching spawning grounds at earlier dates but spawning still occurs at the same time in the fall. Hence, adult sockeye are spending more time in freshwater, and this leads to "premature" exhaustion of energy reserves, longer times for disease to incubate, etc. Net result is greater pre-spawn mortality. A similar disconnect occurs during the downstream migration of young anadromous fishes -- their freshwater habitats are changing at a differnet rate than their marine environment, so young may arrive to the ocean before the ocean has reached sufficient productivity. Although not a precise example, the work of Holtby et al from Carnation Creek BC Canada serves as a good empirical example of how disruption of the timing between life history events has non-linear long term population consequences.
Cheers, Michael Cooperman, PhD. -----Original Message----- From: Ecological Society of America: grants, jobs, news [mailto:[email protected]] On Behalf Of Scott Ruhren Sent: Friday, March 23, 2012 9:28 AM To: [email protected] Subject: Re: [ECOLOG-L] effects of early spring on fish spawning? Hi David, River herring (common name blue-back herring and alewife, anadromous Alosa species) have been spotted already far upstream and that is early for RI. Scott Ruhren, Ph.D Senior Director of Conservation Audubon Society of Rhode Island 12 Sanderson Road, Smithfield, RI 02917 Tel: 401-949-5454 ext. 3004 Fax: 401-949-5788 [email protected] Connecting People With Nature Stay informed all month long with eWing, Audubon's monthly e-newsletter. Follow us online: www.asri.org ~ Twitter ~ Facebook Consider supporting Audubon by making a donation today! -----Original Message----- From: Ecological Society of America: grants, jobs, news [mailto:[email protected]] On Behalf Of David Inouye Sent: Thursday, March 22, 2012 2:42 PM To: [email protected] Subject: [ECOLOG-L] effects of early spring on fish spawning? The Diane Rehm show on WAMU this morning featured an hour about the effects of the mild winter and early spring: http://thedianerehmshow.org/shows/2012-03-22/effects-mild-winter Audio recorded at: http://thedianerehmshow.org/audio-player?nid=15792 One question that came up was about the potential consequences of early spawning by largemouth bass and other fish. My guess was that there weren't likely to be potential consequences such as were experienced by plants, insects, and other animals in 2007, when an early warm spell in March like this year's was followed by a hard freeze in April. But I'd be interested to hear from aquatic/fish biologists who are more knowledgeable. David Inouye Dr. David W. Inouye, Professor Associate Chair, Director of Graduate Studies Dept. of Biology University of Maryland College Park, MD 20742-4415 Rocky Mtn. Biological Laboratory PO Box 519 Crested Butte, CO 81224 [email protected] 301-405-6946
