Striped Bass Status

Striped Bass (stripers) came from New Jersey by train in milk cans 135 years ago to provide a vibrant commercial fishery and regional food supply. Today, stripers remain a prized gamefish in Central Valley rivers, the Delta, and the Bay. Like the native smelts, salmon, steelhead, herring, and sturgeon, stripers have undergone a dramatic decline over the past several decades (Figure 1). Many have blamed the stripers for these declines, when in fact the entire fish community and food-chain of the Bay-Delta has suffered from the man-made spring-summer droughts in the Central Valley. Stripers may prey on listed salmon, steelhead, and smelt, but are far more likely to prey upon native and non-native competitors and predators of these listed species.

Despite their strong inherent ability to recover (high reproductive capacity and long life 1 ), stripers have declined in abundance from 3-5 million adult fish in the 60s and 70s to less than a half million adults in recent years (CDFW unpublished data). A hatchery and pen-rearing program in the late 1990s and early 2000s released millions of young stripers, which led to some recovery in young production (Figure 1) and adult catch (Figure 2). Today, all indications are that stripers are now at record low levels. Stripers are one of the species identified as suffering in the Bay-Delta’s Pelagic Organism Decline2. Their decline can be directly related to Delta water exports, especially in summers of dry years since 1995, when summer protections for stripers were removed from Bay-Delta water quality standards.

Despite low adult numbers and poor summer Delta habitat conditions, recent production of young stripers in wet years is consistent with recent historical levels (Figures 3 and 4). However, production of young is very low in dry years (Figure 5). The reason for the difference between wet and dry year survival is the location of low-salinity nursery habitat in the estuary (Figures 6, 7, and 8). Young stripers are more vulnerable to Delta exports in dry years when Delta inflows are low and their Low Salinity Zone3 nursery area is located in the Delta (Figure 9).

What can be done to help stripers and the striper fishery?

  1. The Low Salinity Zone of the estuary must be kept out of the central Delta by providing sufficient Delta outflow. This would help to keep Delta pelagic fishes and their planktonic food-chain (as well as salt) out of the export pumps.
  2. Stripers should be relocated from below Central Valley river diversion dams where stripers concentrate in summer and become a localized predatory nuisance. (Such locations are generally closed to fishing.) Stripers should be relocated to Central San Francisco Bay where they support a valuable sport fishery and there are other sources of prey.
Figure 1. Young Striped Bass summer (A) and fall (B) abundance indices.  (Source: CDFW)

Figure 1. Young Striped Bass summer (A) and fall (B) abundance indices. (Source: CDFW)

Figure 2.  Striped Bass adult catch pattern in Bay-Delta sport fishery. ( Source:  CDFW)

Figure 2. Striped Bass adult catch pattern in Bay-Delta sport fishery. ( Source: CDFW)

Figure 3.  Young Striped Bass density distribution in July 1995 20-mm Survey.

Figure 3. Young Striped Bass density distribution in July 1995 20-mm Survey.

Figure 4.  Young Striped Bass density distribution in July 2011 20-mm Survey.

Figure 4. Young Striped Bass density distribution in July 2011 20-mm Survey.

Figure 5.  Young Striped Bass density distribution in July 2014 20-mm Survey.

Figure 5. Young Striped Bass density distribution in July 2014 20-mm Survey.

Figure 6.  Young Striped Bass density distribution in June 2015 20-mm Survey.

Figure 6. Young Striped Bass density distribution in June 2015 20-mm Survey.

Figure 7. Catch distribution of young Striped Bass in Summer Townet Survey July 2011, a wet year.  Magenta line is 2640 EC salinity (commonly referred to as X2).  Green line in 500 EC salinity

Figure 7. Catch distribution of young Striped Bass in Summer Townet Survey July 2011, a wet year. Magenta line is 2640 EC salinity (commonly referred to as X2). Green line in 500 EC salinity

Figure 8.  Catch distribution of young Striped Bass in Summer Townet Survey July 2014, a drought year.  Magenta line is 2640 EC salinity (commonly referred to as X2).  Green line in 500 EC salinity.

Figure 8. Catch distribution of young Striped Bass in Summer Townet Survey July 2014, a drought year. Magenta line is 2640 EC salinity (commonly referred to as X2). Green line in 500 EC salinity.

Figure 9.  The mechanism for poor Striped Bass survival in summers of dry years is larval and juveniles being drawn from north to south across the Delta to the south Delta export pumps (blue box).  The Low Salinity Zone is in Delta and is continually degraded by loss to pumps.  Magenta line is the approximate location of 2640 EC salinity (about 2 ppt salinity, commonly referred to as X2).  Green line is the approximate location of 500 EC salinity, generally considered the upper extent of the Low Salinity Zone.

Figure 9. The mechanism for poor Striped Bass survival in summers of dry years is larval and juveniles being drawn from north to south across the Delta to the south Delta export pumps (blue box). The Low Salinity Zone is in Delta and is continually degraded by loss to pumps. Magenta line is the approximate location of 2640 EC salinity (about 2 ppt salinity, commonly referred to as X2). Green line is the approximate location of 500 EC salinity, generally considered the upper extent of the Low Salinity Zone.

  1. http://www.dfg.ca.gov/fish/Resources/Striped_Bass/Biology.asp
  2. http://www.science.calwater.ca.gov/pod/pod_index.html
  3.  The Low Salinity Zone is defined as the location of brackish water with salinity of 1-6 parts salt per thousand in water as compared to 32 ppt in seawater.

Wild Salmon – A Superfood

salmon for dinnerRecently, I had fresh, wild, troll-caught1 Coho from Costco ($4.99/lb whole) with wild rice and fresh strawberry walnut salad. The salmon was truly delicious as is the usual case with fresh, wild, troll-caught salmon.

Wild salmon like this is a “Super Food”.

“Salmon is a great source of protein and is packed with omega-3 fatty acids, which are associated with a healthy heart and brain function. Look for wild salmon to get the biggest health boost.” http://partnersinhealth.kaiserpermanente.org/july-2015/national/10-superfoods-that-pack-a-nutritional-punch-nat-july2015#sthash.hUM61ZOx.dpuf.

“Fatty ocean fish such as salmon and tuna are high in omega-3 fatty acids and can help reduce cholesterol levels, especially when you eat fish instead of saturated fats from red meats. Herring, trout and sardines are also high in omega-3s. Fish is also high in protein and minerals.”
http://nutrition.about.com/od/cardiovascular/ss/Super-Foods-that-Lower-Cholesterol.htm#step10

Having wild salmon available in markets is a very strong reason for upgrading the Central Valley Fall Run Chinook Salmon hatchery program, as I have advocated in earlier posts. Demand for salmon will be increasing as more and more Californians become health conscious. With the public recognition that farmed salmon are not “wild” salmon, there will be further pressure to increase production of “wild”, “free range” salmon in our coastal waters. Central Valley salmon hatcheries can help meet this need.

Approximately 90% of the coastal “wild, free-range” salmon come from the many federal, state, and tribal hatcheries on Pacific Coast rivers.

However, hatchery salmon and the fisheries they support can be a threat to native non-hatchery wild salmon runs, many of which have been listed as threatened or endangered under federal and state endangered species acts. Fishery harvest pressure on these non-hatchery “wild” salmon like the listed Winter Run and Spring Run Chinook of the Sacramento River, potentially put these runs at greater risk of extinction. With the greater risk comes fishery restrictions and less harvest of hatchery salmon, and the need for careful planning and management of the hatchery programs and fishery harvest. Harvest can be focused on times and locations where endangered salmon are least frequently present, but often this may not be possible. Other measures such as gear and catch restrictions, terminal fisheries, and mark-selective fisheries could be employed, making it possible to “have our salmon and eat them too!”

  1. Troll-caught salmon are from regulated commercial fisheries in coastal waters from California to Alaska. They are caught live on trolling lines (in contrast to gill nets) and placed immediately on ice. I avoid purchasing “wild” salmon products from Russia or China that are available in grocery stores, because they come from “unregulated” fisheries, possibly even illegally from North American waters. Gill nets up to 50-miles long have been found fishing in ocean waters. I never purchase farmed salmon, which have little of the nutritional benefits of wild salmon.