5. Forage Fishes

Background

Forage fishes are small schooling fishes that form a critical link in the marine food web between zooplankton and larger fish and wildlife consumers. They occupy every marine and estuarine nearshore habitat in Washington, and much of the intertidal and shallow subtidal areas of the Puget Sound Basin are used by these species for spawning habitat. Status of forage fish populations can be an indicator of the health and productivity of nearshore systems (PSP 2009). Information on forage fish life history, distribution, and habitat preferences is summarized in Marine Forage Fishes of Puget Sound (Penttila 2007) and the Forage Fish Management Plan (Bargmann 1998).

The three most common forage fish species in the Puget Sound basin are Pacific herring (Clupea pallasi), surf smelt (Hypomesus pretiosus), and Pacific sand lance (Ammodytes hexapterus), and are therefore the focus of this section.

Pacific Herring

Pacific herring (Clupea pallasii)

Pacific herring (Clupea pallasii). Image courtesy of NOAA.

Pacific herring are a pelagic fish species found from northern Baja California to northern Honshu Island, Japan. They are found throughout the Puget Sound basin and are a mix of “resident” and “migratory” stocks (Gao et al. 2001, Penttila 2007, Stick and Lindquist 2009). Migratory populations cycle between the winter spawning grounds in the inside waters and the mouth of the Strait of Juan de Fuca in the summer, while resident stocks reside in the inside waters year-round (Penttila 2007). The faster individual growth rates observed in some herring populations are thought to be the result of fish leaving Puget Sound to feed in more productive oceanic waters and thus help to differentiate between migratory and resident stocks. For example, the Squaxin Pass herring population has a slower growth rate and is classified as “resident” while the Cherry Point population has a faster growth rate and is classified as “migratory” (Stick and Lindquist 2009).

Herring spawning occurs between January and April, with the majority of spawning taking place in February and March. Herring become ready to spawn over a two-month period by moving from deep water into shallow nearshore areas. The large natural and decadal oscillations in herring stock abundance are reflected in the area of spawning used annually. Most spawning areas appear to have “outlier” areas, used only during periods of high stock abundance, and “core” areas, used during periods of low stock abundance (Penttila 2007). Herring spawn on benthic marine macro-vegetation such as eelgrass or red macroalgae in the shallow subtidal and low intertidal region. Herring spawn preferentially in sheltered bays as opposed to vegetation beds on adjacent open shorelines (Stick and Lindquist 2009) (Figure 1).

 

Figure 1

Figure 1. Documented Pacific herring spawning areas in Puget Sound (reprinted from Stick and Lindquist 2009 with permission from Washington Department of Fish and Wildlife).

Within the Puget Sound basin, autonomous stocks of herring are defined as having geographically distinct spawning areas and seasons. Two herring populations are deemed genetically distinct from other Puget Sound: the Cherry Point population which is distinctive for its late spawn timing (Small et al. 2005, Beacham et al. 2008, PSP 2008) and the Squaxin Pass population (Stick and Lindquist 2009)(Figure 1), which is thought to be spatially isolated from other populations (Small et al. 2005). Other sampled herring stocks show no evidence of genetic distinction (Small et al. 2005, Beacham et al. 2008), suggesting that these stocks may be part of a metapopulation where sufficient gene flow reduces genetic divergence (Stick and Lindquist 2009). If Puget Sound herring stocks act as a metapopulation, it may be more relevant to examine abundance trends on a larger scale than individual stock level, with Cherry Point and Squaxin Pass being the exceptions (Stick and Lindquist 2009).

Surf Smelt

Surf smelt (Hypomesus pretiosus)

Surf smelt (Hypomesus pretiosus). Image courtesy of NOAA.

Surf smelt are a nearshore species found from Long Beach, California to Chignik Lagoon, Alaska. They occur throughout the marine waters of Washington and in the southernmost region of Puget Sound. For the duration of their lifespan, surf smelt appear to inhabit shallow nearshore zones in the general area of their spawning (Penttila 2007).

Surf smelt spawning habitat is distributed throughout the Puget Sound basin and over a broad variety of conditions (e.g., variable salinity or shading). Spawning areas are usually occupied during summer (May-August), fall-winter (September-March), or year-round (monthly spawning with a seasonal peak)(Bargmann 1998, Penttila 2007). Spawning beaches are used on an annual basis, and as with Pacific herring, surf smelt have been shown to utilize “outlier” spawning sites during periods of high stock abundance (Penttila 2007).

Surf smelt use predictable shoreline areas for spawning across seasons; all spawning beaches first mapped by the Washington Department of Fish and Wildlife (WDFW) in the 1930s are still used by surf smelt. The critical habitat elements for spawning are substrate and tidal elevation. Surf smelt spawn in the uppermost one-third of the tidal range and most beaches appear suitable for surf smelt spawning habitat ranging from sheltered beaches to fully-exposed pebble beaches (Penttila 2007). Due to the diffuse nature of surf smelt spawning habitat there are no obvious grounds for stock definition in geographical terms.

Pacific Sand Lance

Pacific Sand Lance (Ammodytes hexapterus)

Pacific Sand Lance (Ammodytes hexapterus). Image courtesy of the U.S.G.S.

The Pacific sand lance occurs throughout the coastal northern Pacific Ocean from the Sea of Japan to southern California, and is widespread within the nearshore marine waters of Washington, including the entire Puget Sound basin. Sand lances inhabit nearshore waters and spawn between November and February. Sites and spawning habitats of sand lance are similar to that of surf smelt: upper intertidal sand and gravel beaches. Sand lance spawning often takes place on beaches at the distal ends of drift-cells, where accretionary shoreforms tend to occur. Because sand lance and surf smelt deposit eggs in the upper intertidal, they are particularly vulnerable to shoreline habitat modifications (Bargmann 1998).

Status

Of the forage fishes reviewed in this document, only Pacific herring populations have been monitored with sufficient detail to permit status evaluation. Surf smelt and sand lance populations are generally not considered threatened or endangered yet their abundances are currently unknown (Penttila 2007, PSP 2007).

Because of the dependence of forage fish on specific macro-vegetation for spawning, both environmental conditions and human activity (e.g., nearshore development) are likely to affect forage fish spawning biomass (Penttila 2007, Stick and Lindquist 2009). For this and other reasons (e.g., the difficulty in sampling adult populations), regulations have focused on managing forage fish spawning habitat. The Washington Administrative Code (WAC) (220-110), state Growth Management Act (GMA), and WDFW Priority Habitats and Species Program (PHS) all identify forage fish habitat as priority conservation “critical areas” or “areas of concern” for forage fish management (Penttila 2007).

Pacific Herring

There are 19 different stocks of Pacific herring in Puget Sound, based on timing and location of spawning activity (Bargmann 1998, PSP 2007). For 2007-2008, less than half of Puget Sound herring stocks were classified as healthy or moderately healthy (Stick and Lindquist 2009)(Table 1). This is similar to the status breakdown for the previous two-year periods (2003-04, 2005-06). The combined spawning biomass for all Puget Sound, excluding Cherry Point, is considered moderately healthy compared to the previous 25-year mean (11,656 tons for 2007-08 compared with 16,263 tons for 25-year mean). The abundance of south and central Puget Sound herring stocks, excluding Squaxin Pass (which is considered healthy at this time), are considered moderately healthy for 2007-08 (Stick and Lindquist 2009)(Table 1). The cumulative north Puget Sound regional spawning biomasses are considered depressed. Cherry Point continues to be considered critical; spawning biomass decreased during 2007 and 2008. Fidalgo Bay has also declined significantly since 1999 (Stick and Lindquist 2009)(Table 1). The Strait of Juan de Fuca regional status has generally been classified as critical, primarily due to Discovery Bay and Dungeness/Sequim Bay stocks suffering serious declines in biomass in recent years (Table 1) (Penttila 2007, PSP 2007, Stick and Lindquist 2009).

Table 1. Puget Sound herring stock status based on previous 2-year mean abundance compared to previous 25-year mean abundance (from Stick and Lindquist 2009).

Region

 

 

 

 

 

 

 

 

 

 

Stock

2008

2006

2004

2002

2000

1998

1996

1994

South Central Puget Sound

Healthy

Healthy

Healthy

Healthy

Healthy

Healthy

Healthy

Healthy

 

Squaxin Pass

Healthy

Mod. Healthy

Healthy

Healthy

Healthy

Mod. Healthy

Mod. Healthy

Mod. Healthy

 

Wollochet Bay

Unknown

Unknown

Unknown

Unknown

 

 

 

 

 

Quartermaster Harbor

Depressed

Mod. Healthy

Mod. Healthy

Mod. Healthy

Healthy

Healthy

Healthy

Healthy

 

Port Orchard-Madison

Healthy

Healthy

Mod. Healthy

Healthy

Healthy

Depressed

Depressed

Depressed

 

South Hood Canal

Mod. Healthy

Healthy

Mod. Healthy

Mod. Healthy

Healthy

Mod. Healthy

Unknown

Unknown

 

Quilcene Bay

Healthy

Healthy

Healthy

Healthy

Healthy

Healthy

Healthy

Unknown

 

Port Gamble

Depressed

Depressed

Depressed

Mod. Healthy

Healthy

Depressed

Healthy

Healthy

 

Kilisut Harbor

Depressed

Depressed

Mod. Healthy

Healthy

Healthy

Mod. Healthy

Unknown

Healthy

 

Port Susan

Mod. Healthy

Depressed

Depressed

Mod. Healthy

Mod. Healthy

Healthy

Depressed

Mod. Healthy

 

Holmes Harbor

Healthy

Healthy

Healthy

Healthy

Depressed

Healthy

Unknown

Unknown

 

Skagit Bay

Healthy

Healthy

Healthy

Healthy

Mod. Healthy

Mod. Healthy

Healthy

Unknown

North Puget Sound

Depressed

Depressed

Depressed

Depressed

Depressed

Depressed

Mod. Healthy

Healthy

 

Fidalgo Bay

Depressed

Depressed

Depressed

Healthy

Healthy

Healthy

Mod. Healthy

Mod. Healthy

 

Samish/Portage Bay

Healthy

Healthy

Mod. Healthy

Healthy

Healthy

Healthy

Healthy

Mod. Healthy

 

Interior San Juan Is.

Depressed

Mod. Healthy

Depressed

Mod. Healthy

Depressed

Unknown

Unknown

Unknown

 

N.W. San Juan Is.

Disappearance

Depressed

Critical

Depressed

Unknown

Depressed

Unknown

Unknown

 

Semiahmoo Bay

Mod. Healthy

Mod. Healthy

Depressed

Mod. Healthy

Depressed

Depressed

Healthy

Healthy

 

Cherry Point

Critical

Critical

Critical

Critical

Critical

Critical

Depressed

Mod. Healthy

Strait of Juan de Fuca

Critical

Depressed

Critical

Critical

Critical

Critical

Critical

Critical

 

Discovery Bay

Depressed

Depressed

Critical

Critical

Critical

Critical

Critical

Critical

 

Dungeness/Sequim Bay

Depressed

Depressed

Depressed

Mod Healthy

Healthy

Healthy

Healthy

Unknown

Puget Sound Combined

Mod Healthy

Healthy

Mod Healthy

Healthy

Mod Healthy

Mod Healthy

Mod Healthy

Healthy

Individual Stock Comparison

2008

2006

2004

2002

2000

1998

1996

1994

 

HEALTHY

6 stocks

6 stocks

4 stocks

8 stocks

10 stocks

7 stocks

7 stocks

4 stocks

 

MOD HEALTHY

3 stocks

4 stocks

5 stocks

7 stocks

2 stocks

3 stocks

2 stocks

5 stocks

 

DEPRESSED

6 stocks

7 stocks

6 stocks

1 stock

3 stocks

5 stocks

3 stocks

1 stock

 

CRITICAL

2 stocks

1 stock

3 stocks

2 stocks

2 stocks

2 stocks

1 stock

1 stock

 

DISAPPEARANCE

1 stock

0 stocks

0 stocks

0 stocks

0 stocks

0 stocks

0 stocks

0 stocks

 

UNKNOWN

1 stock

1 stock

1 stock

1 stock

1 stock

1 stock

5 stocks

7 stocks

 

 

47%

56%

50%

83%

71%

59%

69%

82%

 

 

Healthy or Mod. Healthy

Healthy or Mod. Healthy

Healthy or Mod. Healthy

Healthy or Mod. Healthy

Healthy or Mod. Healthy

Healthy or Mod. Healthy

Healthy or Mod. Healthy

Healthy or Mod. Healthy

Pacific Herring

The cumulative spawning biomass of all Puget Sound herring stocks, except the Cherry Point stock, has fluctuated between about 10,000 to 16,000 tons (PSP 2009, Stick and Lindquist 2009) (Figure 2). Stocks in south and central Puget Sound have exhibited a general increasing trend, however this may be due to increased sampling effort since 1996. If the abundance of stocks are assumed to be at their mean levels during years when data are not available, then the estimated aggregate population sizes in the south and central Puget Sound stocks are comparable to those from 1970s and 1980s. Stocks in northern Puget Sound, excluding the Cherry Point stock, have remained at a low level of abundance (PSP 2009, Stick and Lindquist 2009) (Figure 2). Similarly, herring spawning biomass in the Strait of Juan de Fuca region continues to be very low and with the exception of 2006, the Discovery Bay herring stock has decreased steadily to between 200-250 tons annually since the mid 1990s (Stick and Lindquist 2009).

Figure 2

Figure 2. Estimated Puget Sound herring total spawning biomass by region and Cherry Point stock, 1976-2008 (data from Stick and Lindquist 2009, reprinted from PSP 2009).

Puget Sound herring stock abundance is significantly affected by mortality rates, which can be attributed to fishing and natural mortality (Stick and Lindquist 2009) (Figure 3). The mean estimated annual natural mortality rate for sampled Puget Sound herring stocks (excluding Cherry Point) since 1990 has averaged 72%, compared with typical mortality rates of 30-40% for herring worldwide. The Cherry Point herring stock annual mortality rate has increased to an average of 68% since 1990. Fishing mortality has averaged about 4% of estimated natural mortality since 1997. Predation, disease, and climatic changes are all potential causes of increased natural mortality (Stick and Lindquist 2009).

Figure 3

Figure 3. Annual tonnage estimates of herring in Puget Sound determined by natural mortality/survival rates, fishery harvest, and cumulative spawning biomass from 1976-2007 (reprinted from Stick and Lindquist 2009 with permission from Washington Department of Fish and Wildlife).

Uncertainties

Since the amount of data collected and the methods used for data collection differ across herring stocks and from year to year, Stick and Lindquist (2009) developed a system to evaluate the quality of the available information for each stock. They designated stocks which had a continuous time series of both acoustic-trawl and spawn deposition data as having “Good” data quality, stocks which had a continuous time series of only spawn deposition data as having “Fair” data quality, and populations for which there was an incomplete time series for either type of data as having “Poor” data quality. The majority of stocks assessed in this manner fell into the “Fair” category, with the best and most consistent data coming from Port Orchard/Madison and Cherry Point (Stick and Lindquist 2009)(Table 2).

Table 2. Puget Sound herring stock data quality determined by the amount of stock assessment data (evaluated in Stick and Lindquist 2009).

South/Central Puget Sound

Data Quality

Squaxin Pass

Fair

Wollochet Bay

Poor

Quartermaster Harbor

Fair

Port Orchard/Madison

Good

South Hood Canal

Poor

Quilcene Bay

Fair/Poor

Port Gamble

Fair

Kilisut Harbor

Fair/Poor

Port Susan

Fair

Holmes Harbor

Fair

Skagit Bay

Fair

North Puget Sound

 

Fidalgo Bay

Fair

Samish/Portage Bay

Poor

Interior San Juan Islands

Poor

Northwest San Juan Island

Poor

Semiahmoo Bay

Fair

Cherry Point

Good

Strait of Juan de Fuca

 

Discovery Bay

Fair

Dungeness/Sequim Bay

Poor

Good: A continuous time series of acoustic-trawl data & spawn deposition data.

Fair: A continuous time series of spawn deposition data only.

Poor: An incomplete time series of either type of stock assessment data.

Summary

Because of their reliance on near-shore habitats, the continued viability of these populations depends on the preservation of this habitat. Pacific Herring have a complicated population structure based on differences in the location and timing of spawning, although only two stocks are deemed genetically distinct. Data on population status are most extensive for Pacific Herring stocks, where current status and trends are mixed. The previously large Cherry Point stock is severely depressed from historical population levels. The prospect that this stock is now regulated by diseases has been raised and remains an active area of research. Long term assessment of other major species is needed to evaluate their current population levels and trends so that the impacts of habitat loss, fishing and climate change can be determined.

Literature Cited

Bargmann, G. 1998. Forage Fish Management Plan. Washington Department of Fish and Wildlife, Olympia, WA.

Beacham, T. D., J. F. Schweigert, C. MacConnachie, K. D. Le, and L. Flostrand. 2008. Use of microsatellites to determine population structure and migration of Pacific Herring in British Columbia and adjacent regions. Transactions of the American Fisheries Society 137:1795-1811.

Gao, Y. W., S. H. Joner, and G. G. Bargmann. 2001. Stable isotopic composition of otoliths in identification of spawning stocks of Pacific herring (Clupea pallasi) in Puget Sound. Canadian Journal of Fisheries and Aquatic Sciences 58:2113-2120.

Penttila, D. 2007. Marine Forage Fishes in Puget Sound. Puget Sound Nearshore Partnership Report No. 2007-03, Seattle, WA.

PSP. 2007. Puget Sound Update: Ninth Report of the Puget Sound Assessment and Monitoring Program. Page 260, Olympia, WA.

PSP. 2008. Species and Biodiversity Topic Forum. Puget Sound Partnership, Seattle, WA.

PSP. 2009. Ecosystem Status & Trends. Puget Sound Partnership, Seattle, WA.

Small, M. P., J. L. Loxterman, A. E. Frye, J. F. Von Bargen, C. Bowman, and S. F. Young. 2005. Temporal and spatial genetic structure among some Pacific Herring populations in Puget Sound and the Southern Strait of Georgia. Transactions of the American Fisheries Society 134:1329-1341.

Stick, K. C., and A. Lindquist. 2009. 2008 Washington State Herring Stock Status Report. Stock Status Report No. FPA 09-05, Olympia, WA.