As we all know, the directed harvest of Pacific Sardine was not allowed for the season running July 1, 2015 – June 30, 2016. We previously provided an explanation on how the harvest level for Pacific Sardine is calculated – see here. In 2015, the adjusted biomass estimate was 96,688 metric tons. This estimate was based, in good part, on average recruitment during the previous years (those years were cold-water La Nina years which typically don’t result in high sardine recruitment). This 96,688 figure was the low estimate, the high estimate was 136,000 mt; but the lower number was recommended because virtually no recruitment was observed.
Because this was less than the cutoff amount of 150,000 mt, no directed non-tribal fishery was authorized. According to reports, the preliminary biomass estimate proposed for the 2016-17 fishery season is a little over 64,000 mt. Once again, the average of the last three year’s recruitment helped to inform this estimate. The model also produced a much higher estimate of 106,000 mt; but that is disfavored by the Assessment’s authors. Both of these numbers ignore the observed recruitment event which we discuss further below.
If the 64,000 mt estimate is approved, it will again result in no directed, non-tribal, fishery for the season running July 1, 2016 – June 30, 2017. Commercial fishermen who target sardines, their families and the coastal communities who rely upon sardine harvest will face further uncertainty and extreme hardship.
Because this is an “update” to an existing stock assessment, very little flexibility if given to scientists and fishery managers to modify the model or methods used to produce the estimate. Further, the current pacific sardine harvest control rule allows no discretion for the Pacific Fishery Management Council and fishery managers to allow a directed non-tribal fishery if the biomass estimate falls below the 150,000mt cutoff. What we do want to call into question are the data and methods used to estimate the biomass.
While we acknowledge the pacific sardine biomass has declined since 2007, we do not believe the decline has been as severe as reported; and there is evidence that populations may be expanding again. Sardine populations have declined in the years since 2007 due to strong La Niña cold-water conditions, not conducive to sardine productivity. A similar situation occurred during the strong La Niña conditions in 1999-2001, when the sardine population also declined rapidly. However, the 2003 El Niño resulted in strong recruitment in the following years, leading to a peak in abundance in 2007. The 2015 El Niño is producing a similar response.
The 2015 Stock Assessment references a “lack of evidence for spawning in 2014”. During the summer of 2015, we were repeatedly told of vast amounts of smaller sardines in various places along the southern California coast and Channel Islands. These were of a size that would have been the result of 2014 and early 2015 spawning. On more than one occasion, we delivered samples of these smaller fish to show there had been recruitment and that some of the assumptions in the 2015 Assessment may prove to be false. Pilots who assist and have assisted California fishermen reported seeing abundant schools of sardine. A pilot who has extensive experience spotting for the Oregon and Washington sardine fishery, was flying his plane from Sitka to Oregon last fall and reported seeing more sardine than he has ever seen. This past weekend, we were told that Monterey Bay has so much sardine in it that vessels hoping to target anchovies are unable to work without the risk of incidentally catching too much sardine. These harvesters and pilots are concerned that the science use to determine biomass is somehow missing a population which is much stronger than presented.
How is the sardine biomass estimated?
The Stock Assessment provides the basis for management decisions impacting the pacific sardine fishery. In recent history, the stock has been fully assessed every three years with updates provided annually. As noted above, this year is an update assessment and a full stock assessment is scheduled for 2017. The assessment is model based, which means certain data are collected and become inputs. The model (think computer program) then produces the output, which for our purpose is the estimated biomass of Pacific sardine age 1 and older. Types of information that provide the data inputs include:
- Landings from the three most recent fishing seasons;
- Size structure of samples collected from those landings;
- Age structure of those same samples;
- A measure of the daily egg production method (DEPM) if an estimate can be provided.
- An estimate of the biomass gathered from spring and summer surveys using the acoustic trawl method.
Possible limitations for each data element
Recent landings. We know that actual landings from the three most recent fishing seasons are collected and broken down by region. These landings are then subtracted from the estimated biomass in helping to inform the next year’s assessment. Is the model robust enough to account for regional fluctuations? The cold water regime we recently experienced was a boom for the California squid fishery. Squid is a much more valuable target than sardine. This led to reduced targeting of sardine in California. Does the model take into account that those fishermen were likely targeting a higher value product – squid or mackerel for example – and that lower sardine landings in California is not indicative of unavailability?
Size and age structure. Sardines harvested off Oregon and Washington tend to be larger than those taken in southern California. As mentioned above, California landings may be artificially low given the availability of higher valued alternatives; consequently, does the model become skewed with a higher percentage of the Harvest Guideline being landed in Oregon and/or Washington? For example, does a higher percentage of larger and older fish inform the model that recruitment events are less than they may have been in reality?
Daily egg production method (DEPM). In the Spring of each year, ship-based surveys are conducted to collect adult sardines and sardine eggs or larvae in fine meshed nets. Between 1994 – 2013, these surveys ran between San Diego and San Francisco. Based on the number of eggs/larvae and adult female sardines, an estimate of the DEPM was derived. In 2014, the survey returned no valid data and thus, DEPM could not be estimated. In November of 2015, the Southwest Fisheries Science Center submitted its Summary of Current Information Available on Coastal Pelagic Species with Emphasis on Northern Anchovy. While the emphasis may have been on northern anchovy, it offered some valuable information on pacific sardine:
- Sardine eggs are rarely found north of San Francisco in the spring, but in 2015 sardine spawned 445–556 km further north than usual (emphasis in original).
- Larval sardine captured during the spring CalCOFI/CPS cruise suggest additional spawning occurred outside the traditional spawning period and thus might negatively impact DEPM value estimates.
- “Pacific sardine eggs were collected from southern California to the Pacific Northwest suggesting that sardine were spawning during June in the southern California Bight, in July off San Francisco, off central Oregon in July and off the Columbia River in August.”
- During a Juvenile Rockfish Midwater Trawl survey for pelagic juvenile rockfish, conducted off the coast of Central California in May and June of 2015, “the abundance of adult Pacific sardine and northern anchovy remained very low, although larval catches for both species were at high or record levels in most areas.”
Have these observations from 2015 been accounted for in determining DEPM moving forward and could they retroactively offer an explanation for the lack of observations in 2014? Regarding the collection of adult sardines and eggs/larvae in towed nets, what effect does a deeper thermocline have on the collection density? Is it likely that if warmer water extends deeper you would expect to see less collectible samples higher in the water column? All of those observations lead to the logical conclusion that spring and early summer of 2015 were banner times for sardine recruitment. These fish would be age 1+ as of July 1, 2016, yet the stock assessment shows a 33% drop in the biomass?
Acoustic Trawl Surveys. These surveys couple acoustic electronic gear (echosounder) with a trawl to validate species measured and captured. For those unfamiliar with echosounder gear, it provides a picture of what lies directly under the vessel. Its coverage is cone shaped – widening as it goes deeper in the water column. In 2011, the Council’s Methodology Review Panel noted, “[t]he transducer is mounted on a blister or keel extending from the vessel hull, precluding observation of animals present nominally 10 m below the surface.” Spotter planes are often used to target sardines, especially off the Pacific Northwest. Most, if not all, of the schools seen by these pilots would be invisible to the acoustic trawl survey vessel. Given the acoustic’s inability to observe the top 10 m of the water column and ineffectiveness in shallow waters, is this a reliable method? Commercial fishermen report that sardines avoid having a vessel drive right over the top of them, couldn’t this artificially lower the estimated school size as the sounder only picks up what is under the vessel. The model assumes that the acoustic trawl method will account for all fish in the surveyed area. This ignores how sardines react to vessels. A new vessel is scheduled to join the research activities in the very near future. This vessel, the Reuben Lasker, is equipped with a side-scanning sonar. Hopefully the Council will prioritize a methodology review which will allow the new research vessel, the FSV Reuben Lasker, to become operational in informing the stock assessment.
We appreciate the complexity surrounding the stock assessment process. We understand that this is not a full stock assessment year; but merely an update. We also acknowledge the harvest control rule offers little discretion once an estimate of the biomass is accepted. We do question the validity of the biomass estimation because it does not reflect what the fishermen and pilots have observed. We think we have raised a number of questions which are worthy of further consideration before the assessment is finalized.
 The Assessment of the Pacific Sardine Resource in 2016 for USA Management in 2016-17 has been made public in a number of places. The title page of the Assessment contains the following, “DO NOT CITE OR DISTRIBUTE WITHOUT PERMISSION FROM THE AUTHORS”. Therefore, we will only reference the biomass estimate which has been widely reported and not any of the other information from the Assessment until it has been released to the public by those with authority to do so.
 This amount has been set aside for ecosystem needs.
 See Page 9 – http://www.pcouncil.org/wp-content/uploads/2015/03/G1a_FullSardine_Assessment_E-ONLY_APR2015BB.pdf.
 Id at 8.
 Id at 2.
 Id at 3.
 See Page 10 – http://www.pcouncil.org/wp-content/uploads/C3a_ATT1_ACOUSTIC_METH_APR2011BB.pdf
 “The Lasker is the fifth in a series of Oscar Dyson-class ships (208 ft; 63m) home ported in San Diego. It is equipped with technologies for fisheries and oceanographic research, including advanced navigation systems and acoustic sensors, five-frequency split-beam echosounders, and scanning, multi-beam and imaging sonars (EK60s, ME70, MS70, SX90). The ship is engineered to produce less noise than other survey vessels and should facilitate studies of fish behavior that could potentially impact our current estimations of sardine as well as other CPS abundance. Regrettably, the first time the SWFSC will be able to use the FSV Lasker to assess sardine will be in the spring of 2016 (30 DAS) and again in the summer of 2016 (78 DAS).” See page 2 – http://www.pcouncil.org/wp-content/uploads/2015/10/H4a_SWFSC_Rpt1_AcousticTrawl_Nov2015BB.pdf