Event Title

New methods improve forage fish egg detection efficiency

Presentation Abstract

As the ecological and commercial importance of forage fish is increasingly acknowledged, more people have begun to sample intertidal habitats to detect the presence of forage fish eggs. To facilitate efforts to study spawning beaches, and data sharing and analysis, we’ve developed alternative methods for rapid processing of standard samples of potential spawning substrate to determine egg presence and estimate relative egg densities. Surf smelt (Hypomesus pretiosus) and Pacific sand lance (Ammodytes hexapterus) provide an important conduit of energy and nutrient from plankton to higher level consumers such as salmon, rockfish, seabirds, and marine mammals. Surf smelt continue to be harvested both commercially and recreationally in Washington State. Both species are intertidal spawners, making their spawning habitat particularly susceptible to anthropogenic impacts from shoreline development. To help protect their spawning habitat, considerable effort has been dedicated to mapping the locations of spawning beaches. Much of the description of the geographic distribution and timing of their spawning has been acquired through the collection, processing, and analysis of sediment samples to detect the presence of eggs. Because the eggs are small and translucent, they are difficult to observe on the beach unless they occur in high densities. We have developed and assessed alternative methods to process bulk sediment samples. Our methods build on the standard methods developed by Moulton and Penttila (2001), but modify them by implementing mechanical means to concentrate the eggs collected from bulk sediment samples. Replacing human winnowing with mechanical winnowing during sample processing helps to standardize processing among individual observers and achieve more consistent results. Our preliminary results indicate that our modifications to the standard methods expedite overall processing time and are more effective at concentrating eggs relative to standard methods. We will share an overview of these alternative methods as well as preliminary results of test trials designed to compare these alternative methods with the current standard methods.

Session Title

Session S-03D: Forage Fish Research and Protection in the Salish Sea

Conference Track

Species and Food Webs

Conference Name

Salish Sea Ecosystem Conference (2014 : Seattle, Wash.)

Document Type

Event

Start Date

1-5-2014 5:00 PM

End Date

1-5-2014 6:30 PM

Location

Room 6C

Contributing Repository

Digital content made available by University Archives, Heritage Resources, Western Libraries, Western Washington University.

Rights

This resource is displayed for educational purposes only and may be subject to U.S. and international copyright laws. For more information about rights or obtaining copies of this resource, please contact University Archives, Heritage Resources, Western Libraries, Western Washington University, Bellingham, WA 98225-9103, USA (360-650-7534; heritage.resources@wwu.edu) and refer to the collection name and identifier. Any materials cited must be attributed to the Salish Sea Ecosystem Conference Records, University Archives, Heritage Resources, Western Libraries, Western Washington University.

Type

Text

Language

English

Format

application/pdf

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May 1st, 5:00 PM May 1st, 6:30 PM

New methods improve forage fish egg detection efficiency

Room 6C

As the ecological and commercial importance of forage fish is increasingly acknowledged, more people have begun to sample intertidal habitats to detect the presence of forage fish eggs. To facilitate efforts to study spawning beaches, and data sharing and analysis, we’ve developed alternative methods for rapid processing of standard samples of potential spawning substrate to determine egg presence and estimate relative egg densities. Surf smelt (Hypomesus pretiosus) and Pacific sand lance (Ammodytes hexapterus) provide an important conduit of energy and nutrient from plankton to higher level consumers such as salmon, rockfish, seabirds, and marine mammals. Surf smelt continue to be harvested both commercially and recreationally in Washington State. Both species are intertidal spawners, making their spawning habitat particularly susceptible to anthropogenic impacts from shoreline development. To help protect their spawning habitat, considerable effort has been dedicated to mapping the locations of spawning beaches. Much of the description of the geographic distribution and timing of their spawning has been acquired through the collection, processing, and analysis of sediment samples to detect the presence of eggs. Because the eggs are small and translucent, they are difficult to observe on the beach unless they occur in high densities. We have developed and assessed alternative methods to process bulk sediment samples. Our methods build on the standard methods developed by Moulton and Penttila (2001), but modify them by implementing mechanical means to concentrate the eggs collected from bulk sediment samples. Replacing human winnowing with mechanical winnowing during sample processing helps to standardize processing among individual observers and achieve more consistent results. Our preliminary results indicate that our modifications to the standard methods expedite overall processing time and are more effective at concentrating eggs relative to standard methods. We will share an overview of these alternative methods as well as preliminary results of test trials designed to compare these alternative methods with the current standard methods.