As county officials revamp streamside development rules intended to protect coho salmon, watershed officials released new numbers confirming an unexpected rebound in the number of the endangered fish’s nests in Lagunitas Creek. The 243 nests, known as redds, counted in the 2012-2013 spawning season represented the highest figure since 2007, according to officials with Marin Municipal Water District. For decades the district has tracked the number of redds in the watershed, a massive set of freshwater sources where as many as one in five of the remaining Central Coast coho start life.
This year’s figure, just under the 18-year average, is up from just 137 last year and a low of 26 redds in 2009. Eric Ettlinger, an aquatic ecologist for the district, said the success of salmon is linked to improving conditions in the Pacific Ocean, where the salmon spend most of their lives.
“There seems to be plenty of food out there,” said Mr. Ettlinger, referring to the small shrimp young coho eat as well as the baitfish and larger fish they consume as they get older. Those creatures are sustained by a complex ecosystem that in recent years saw a smaller plankton bloom, leaving many coho and other fish starving. “The biggest factor is an improvement in ocean conditions in the last few years. What’s really been dominating things since about 2008 was a collapse in the marine food web and the causes for that are still not fully understood, but there was a real decrease in ocean productivity, and we had marine mammals stranding themselves, we had seabird colonies being abandoned.”
The healthy salmon spawning season comes as West Marin property owners, advocates for the endangered species and county officials are debating an updated streamside development ordinance proposed by the county. The policy would waive permit requirements for minor property improvements and would enhance conservation efforts by preventing some development close to waterways.
The Salmon Protection and Watershed Network (SPAWN), a conservation group involved in protracted litigation with the county over coho protections, has pushed for the proposed ordinance to place a higher burden on developers to prove they will mitigate environmental impacts. A public hearing is scheduled with the Marin Planning Commission on April 1 at 10 a.m. at the Civic Center.
Mr. Ettlinger said these sorts of measures, including a massive state and federal effort announced in January, are notable, but may not be all that is needed to save the coho given the increasing water temperatures and rainfall—which salmon need to navigate the creek during spawning seasons that peak in January and can end as late as March—associated with climate change. “These are the best means to conserve them over the long term, but there are a lot of forces at work pushing salmon numbers toward extinction,” he said. “Of the things that we can control, limiting development along salmon streams, limiting inputs of sediment and pollutants, providing shelter and habitat for fish—those are the kinds of things that have been shown to be successful.”
Fishing records and other data show that Central California Coast coho populations have declined markedly—by as much as 95 percent, according to SPAWN—since development increased before the middle of the last century. Retention of coho in California has been banned since a 1996 declaration that the species was threatened; in 2005 their status was downgraded to endangered.