BY MERIT McCREA
SACRAMENTO – Part of the requirements of the Marine Life Protection Act (MLPA), which supported a re-organization of California Marine Protected Areas, most of which primarily limit fishing access, is monitoring and periodic performance review.
This “re-organization” outwardly resulted in a massive increase in the area of state waters off limits to fishing, with a network of new large Marine Protected Areas (MPA) established we are now familiar with. The 10-year review of the monitoring, science and results is out. Here are some key findings:
- Neither rocky reef nor high-quality habitat is uniformly distributed across the state. Both Northern and Central California have more high-quality rock habitat than Southern California. Additionally, SMRs (State Marine Reserves) have more rock and more high-quality habitat than SMCAs (State Marine Conservation Area).
- Fish densities have increased over time throughout the state, due to good recruitment years for many species and to the restrictive fishery management regulations in the last 20 years.
- Reserve effects varied across species, MPAs, management regions, and years. However, some species showed clear positive reserve effects. For example, in the South Region, Copper Rockfish densities were consistently higher inside MPAs relative to outside MPAs in all years surveyed.
- Structure-forming invertebrates, such as corals and sponges, were found at greater densities within MPAs than in associated Reference sites.
- Results of MPA and fishery management measures are intertwined; for example, California sea cucumbers showed a positive reserve effect across the South management region due to fishing closures and the Rockfish Conservation Areas helped rebuild rockfish populations across the state. • Priorities for ROV sampling of mid-depth habitats have been to survey as many MPAs as possible in a given year. This has resulted in inconsistencies in ROV sampling over time and space, making it difficult to compare surveys across years.
- OPC-sponsored work has shown that current ROV sampling levels are sufficient to detect only large statistical differences in fish populations. Sample sizes need to be larger to detect smaller changes.
- Lightweight, relatively inexpensive BRUVs and larger Tethered Video Landers work well for the middepth habitat in California and can compliment ROV sampling. In addition to MPA monitoring, these tools show promise for collecting data that could be used in fisheries management, invasive or rare species monitoring, and documentation of range extensions.
- Results of the seafloor habitat analyses can be used to distribute survey effort from the three visual tools more effectively throughout MPAs and adjacent reference sites by stratifying by habitat quality and reef patch size.
I’ve dug through a bit of the document and the supporting science work provided at the Ocean Protection Council’s (OPC) MPA monitoring web page. First, there is a decided slant to the narrative in the newly-published piece. Basically that narrative is MPAs are good, and here’re some reports on the scientific work to support it.
A closer look at the actual science reports provided by scientists involved in monitoring – gathering, processing and analyzing data – offers a less biased perspective however.
For example with respect to climate change, the marine heatwave and resiliency, while the report said, “Some ecological communities demonstrated greater resiliency inside MPAs compared to those outside of MPAs and recovered more quickly after the heatwave, though analysis across habitats in the central coast revealed that MPAs did not provide strong resilience against the marine heatwave.”
However, in their report to the OPC and California Department of Fish and Wildlife (CDFW)the scientists themselves said, “In Central California, some ecological communities in SMRs experienced less change than in associated reference sites, but across all monitoring groups and MPAs, there was no overarching effect of MPAs in mitigating change.
So you can see there is some subtle difference in the way the published report relates what the scientists themselves said.
During the process of designating MPAs there were multiple habitat types stakeholders were compelled to include within them, for example estuaries, rocky shoreline, beaches and rocky and soft bottom areas in shallow sub-tidal, mid-depth and deep waters.
For the purposes of being included as meeting spacing goals only MPAs of greater than 3 miles of coastline, out to the edge of state waters counted. So one would conclude monitoring would include each of these backbone large MPAs and each of these habitats.
The scientific support for monitoring was fairly comprehensive for the near-shore and out to around 80 feet in rocky bottom habitats. But for the much more prevalent sub-tidal soft bottom habitats and both rocky and soft bottom beyond that depth the science was pretty limited.
There was better coverage mid-depth, (30 down to 100 meters) than soft bottom habitats, but that was still fairly limited. They brought in older manned submersible survey data from non-MPA directed efforts, some limited new MPA Monitoring supported Remotely Operated Vehicle data from a group called MARE, some new video camera data and fishing data from the California Collaborative Fisheries Research Program or CCFRP. It’s this kind of habitat that is most important to the recreational angler.
As for soft bottom habitats beyond the surf line which comprise the bulk of MPAs by percentage area, it appears there was no directed MPA monitoring undertaken. There were at least a few backbone MPAs that saw little if any MPA scientific work, including the Richardsons Rock SMR, which includes some of the highest levels of mid-depth rocky bottom, ranking no. 3 among all state MPAs.
Scientists reporting on mid-depth rocky ecosystems listed these key findings within the executive summary of their report.
Among their recommendations was: Surveys should be stratified by habitat types and depths. Deeper habitats and SMCAs have been undersampled and deserve more attention, as they are de facto MPAs for many species. More surveys should occur in habitats deeper than 50 m to encompass the full range of depths inhabited by target species.
At the same time, authors recognized the limited nature of funding available to support such work, resulting in a further recommendation to monitor fewer MPAs each year in order to provide for sampling at regular intervals within a given MPA.
My thought is if the state doesn’t find MPA monitoring important enough to fund the scientific effort needed monitor each of the required habitat types within each backbone MPA, then perhaps we should consider returning public access for fishing within those MPAs were the monitoring goal of the MLPA isn’t being met.
This thought is especially salient where multiple large MPAs are just a few miles apart and adaptively opening one won’t create a spacing gap which impacts the MLPA’s network goal.
Case in point, Richardson’s Rock SMR is just 4 miles distant from the equally huge Harris Point SMR. As far as I’ve been able to ascertain, the only limited MPA science to date has occurred in the latter.
As far as biomass of fished species between MPA and fished reference sites there were mixed results showing in the mid-depth scientific document, however there was a strong increase noted over time for all areas, likely a result of coast-wide fishery conservation measures taken and coast-wide environmental conditions.
In contrast with the results of the most recent copper rockfish stock assessment, which showed a drastically low result, the ROV data showed the reverse, “Copper Rockfish densities increased through time in both MPAs and Reference sites for all three regions.”
It also revealed, “Additionally, in the South region, Copper Rockfish densities were higher inside the MPAs compared to Reference sites and the difference among MPAs and Reference sites increased through time.”
Thus, the copper rockfish stock assessment currently restricting shallow water rockfish seasons further missed the boat by not including data from within areas closed to fishing. Such stock assessments are based on the reproductive potential of the standing stock, so all areas should be considered, not just those where fishing occurs.
Merit McCrea is saltwater editor for Western Outdoor News. A veteran Southern California partyboat captain, he is a marine research scientist with the Dr. Milton Love Lab at the University of California at Santa Barbara’s Marine Science Institute. He serves on the Groundfish Advisory sub-Panel of the Pacific Fisheries Management Council, the Santa Barbara Harbor Commission, The Channel Islands National Marine Sanctuary Advisory Council and the CCA-Cal State Board. He can be reached at: merit@wonews.com