Abstract Title

Session S-10D: Cross-Habitat Linkages and Landscape Scale Approaches to Ecosystem Management

Keywords

Species and Food Webs

Start Date

2-5-2014 1:30 PM

End Date

2-5-2014 3:00 PM

Description

It is well known that Pacific herring migrate into areas of Puget Sound each winter and spring and spawn on submerged vegetation in shallow nearshore waters. However, we do not understand how the availability and quality of nearshore spawning habitat affects herring egg survival or herring populations. To understand the interplay between nearshore habitat and herring egg success, we measured the survival of wild spawned herring eggs from 5 Puget Sound populations under field and laboratory conditions. We estimated enormous variation in herring egg loss among sites under both field conditions (range of daily loss rates: 5 to 70%) and laboratory conditions (mortality ranged from 20 to 100% over the ~ 7 day incubation). Taking egg loss and mortality rates together with predictions based on field incubation temperatures, we estimated herring hatch probabilities ranging from 0.25 to 10-9. Egg loss and mortality rates varied by site, but not by spawning substrate type. Exploratory analyses revealed the potential influence of wave action and shoreline urbanization on probabilities of hatch success. Using historical records of herring spawn, we determined that herring eggs are not found on any substrate type in greater proportions than expected by chance, with the exception that they are more likely to be found on the non-indigenous brown alga, Sargassum muticum. Last, we found that a large proportion of suitable spawning habitat available to Puget Sound herring at these sites remains unused. Our results demonstrate that Puget Sound herring at these sites are not limited by the amount of suitable spawning substrate, and that native vegetation is not preferred over other vegetation types for herring spawning. Rather, it appears that other land-based or oceanographic variables are more important for determining herring hatch success in Puget Sound.

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May 2nd, 1:30 PM May 2nd, 3:00 PM

Herring reproductive success in Puget Sound: spawning habitat availability and quality, spatial variation in egg survival, and the specter of habitat limitation

Room 611-612

It is well known that Pacific herring migrate into areas of Puget Sound each winter and spring and spawn on submerged vegetation in shallow nearshore waters. However, we do not understand how the availability and quality of nearshore spawning habitat affects herring egg survival or herring populations. To understand the interplay between nearshore habitat and herring egg success, we measured the survival of wild spawned herring eggs from 5 Puget Sound populations under field and laboratory conditions. We estimated enormous variation in herring egg loss among sites under both field conditions (range of daily loss rates: 5 to 70%) and laboratory conditions (mortality ranged from 20 to 100% over the ~ 7 day incubation). Taking egg loss and mortality rates together with predictions based on field incubation temperatures, we estimated herring hatch probabilities ranging from 0.25 to 10-9. Egg loss and mortality rates varied by site, but not by spawning substrate type. Exploratory analyses revealed the potential influence of wave action and shoreline urbanization on probabilities of hatch success. Using historical records of herring spawn, we determined that herring eggs are not found on any substrate type in greater proportions than expected by chance, with the exception that they are more likely to be found on the non-indigenous brown alga, Sargassum muticum. Last, we found that a large proportion of suitable spawning habitat available to Puget Sound herring at these sites remains unused. Our results demonstrate that Puget Sound herring at these sites are not limited by the amount of suitable spawning substrate, and that native vegetation is not preferred over other vegetation types for herring spawning. Rather, it appears that other land-based or oceanographic variables are more important for determining herring hatch success in Puget Sound.