Dive Dry with Dr. Bill

#330: Why We Need Marine Reserves, Part III: Design Criteria

The third column in this series looks at factors that need to be considered in designing a marine reserve, and what constitutes a good network of such reserves throughout our region and the state. The goals are to protect not only our native ecosystems for their own sake and the enjoyment of no take recreators, but also to provide enhanced fish stocks for anglers who likewise enjoy being out on our waters. Back in 1990 I started focusing much of my scientific research on what might constitute a good series of marine reserves around Catalina Island. That work built on my previous research into kelp forest ecology, larval dispersal of marine critters, and dispersal via drifting kelp rafts. In fact, my entire 719 page Ph.D. dissertation focused on this topic. If you ever develop a really bad case of insomnia, try reading it late at night! You'll be one of the few that has... although the research has been published in international journals and presented at many scientific conferences (in greatly abridged versions I should add).

I looked at the existing set of marine protected areas (MPAs) around the island as of 1990. Many such as Lover's Cove, and to a lesser extent the Blue Cavern Refuge were designated based on recreational or educational reasons. I contend that the ecology of Lover's Cove has been substantially altered due to decades of fish feeding, and the fish populations there (albeit very abundant) are not necessarily representative of natural marine ecosystems. Many also assume the Dive Park is a fully protected reserve, which it isn't... although we try to treat it as such. Other areas of the island such as Farnsworth Bank were established as Areas of Special Biological Significance in the late 1970's based on factors such as the presence of the purple hydrocoral. The West End Invertebrate Reserve protected critters without backbones from Lion's Head Point to Arrow Point.

However, few of these existing MPAs were established based strictly on scientific, ecological criteria. Many of them were too small to offer much real protection... or spillover for anglers. They were also not designed as a cohesive network of reserves that included obvious pathways for egg, larval or adult dispersal of fish and invertebrates between them. As an undergraduate at Harvard, I had studied island biogeography under the renowned Professor E. O. Wilson. Much of my research then, which was the reason I came to teach on our island in 1969, had relevance for the design of nature reserves on land as well as in the ocean. This subject became one of my passions (in addition to Catalina, pan dulce, flank steak... and beautiful, intelligent mermaids).

Individual reserves need to be designed based on the unique group of species in their ecosystem. Their ecological relationships, feeding patterns, territoriality, reproductive patterns and other life history information should be assessed. My research on island reserves looked at habitats around the entire island's 54-mile coastline, and determined where kelp forests were either most resistant to disturbance by storm or elevated temperatures like El Ninos, or at least resilient... bouncing back in the face of such disturbance. These areas of persistent giant kelp around the island served as indicators of where rocky reef fish populations might be most stable. The potential reserve areas identified included both the windward and leeward sides of the West End, the region between the mouth of Catalina Harbor down to Ben Weston, and the large beds from China Point to Salta Verde. Of course these did not identify areas of good soft bottom habitat, since kelp attaches only to rock, nor regions in unusual habitats like the warm water area from Long Point to the East End where El Ninos often have their strongest impact.

Networks of reserves must be designed to ensure each one enhances and amplifies on the benefits of the others. An important factor in looking at networking reserves is the prevailing current direction. Currents help disperse eggs, larvae and even adults from one reserve to another, and to unprotected areas as well. Some reserves must be positioned down current from others to ensure dispersal and therefore gene flow between them. Since the currents here run primarily from northwest to southeast along both coasts, portions of the leeward and windward sides of the West End were a good place to start. These are also colder water habitats than those further south on either side of the island based on my analysis of sea surface temperature satellite images. New reserves added further south on each coast would allow larvae to be captured by the kelp forests, and replenish both protected and unprotected areas. However, to site a reserve at the East End would result in larval dispersal drifting off into outer space... er the open ocean. A reserve there would not be as useful in maintaining marine populations around the island unless unique species are found there (and some are)!

To design marine reserve networks on an ecological basis (the goal of the Marine Life Protection Act or MLPA) requires many other factors to be considered. Information about the size of breeding stock, growth rates, reproductive capacity, the habitat needs for each stage in a species' life cycle, and genetic diversity are just a few that need to be incorporated in the design criteria. Optimum reserve size is also an important design factor, and depends on the species present in the ecosystem and their movements. Large reserves protect more species, greater population sizes (and therefore higher reproduction) and more diversity. However in some cases a network of smaller reserves may achieve some of the same goals without imposing restrictions over too large an area, causing fewer economic dislocations. But these smaller reserves have lower potential to contribute spillover to the adjacent unprotected areas to provide fish for anglers. Studies have indicated that 20-60% of a population needs to be protected to achieve a sustainable yield allowing fishing to be successful over long periods of time.

Looking at the various plans proposed for Catalina's reserve network by stakeholder groups (viewable at the web site, some plans offer absolutely no new protection. They simply keep some of the existing ones and add the dive park into the mix. An example was the proposal by the Lapis working group shown in last week's column. That plan would actually reduce already existing protected areas, and defeat the entire purpose of the MLPA. Proposals like External Proposal C have been termed as too extreme by some, yet they are actually much more realistic from an ecological perspective... with one important exception. It has been recommended by the State that all reserve boundaries extend out to the 3-mile state limit.

Here I strongly agree with the fishing community. I feel this is totally inappropriate for our island waters as it greatly reduces the area anglers could troll for open water (pelagic) species, which I feel is unfair to the fishing community. Three miles off Catalina, especially on the leeward side, could place one in waters 1,000 feet deep or more due to the steep underwater topography. The equivalent distance off the mainland coast might place you in only 150-200 feet of water and mainland fish in those depths would benefit greatly from that protection. I have suggested to other scientists and participants in the MLPA process (and do so again in this column) that they consider a depth based limit much closer to shore rather than extending protection all the way out to the 3-mile limit. Perhaps a limit out to a depth of 300-400 feet would be appropriate.

A network of coastal reserves off the island should not affect open water or pelagic fisheries such as swordfish or marlin, which are migratory species. An exception would be for such species that utilize nearshore habitats as feeding or nursery areas, and those protections come with the depth-based limit. Reserves also do not address issues like pollution, fertilizer or human waste runoff from land, the appearance of invasive species like the Japanese Sargassum filicinum kelp, disease or climate change. In fact reserves should not be placed in areas known to be affected frequently by such factors.

We do know that properly designed reserves create higher fish and invertebrate densities, longer survival, larger average sizes of individual fish, higher reproductive rates and higher species diversity for most species than unprotected areas. You can pretty much take that to the bank. And speaking of the banks... are we going to let our marine ecosystems reach the crisis encountered recently by our financial system? Are we going to take away the birthright of our children and grandchildren to fish, or take fish pictures, in waters teeming with them? There may not be a bailout for our marine life if we don't act soon. Yes, there will be some short-term pain, some sacrifice to ensure long-term gain. I know there are many anglers who realize this (and a few divers who don't). I think the time is now to act to save our marine ecosystems for their intrinsic ecological value, their recreational value and their economic value.

Recently we've seen what happens when businesses take a short-term view and maximize immediate profits without sufficient consideration for the long-term effects on their own businesses, or on others. If we, today, take the same view, and do not adequately protect our marine ecosystems, I seriously question whether our children and grandchildren will be able to enjoy our waters and their marine life in future decades. Had our grandparents and great-grandparents created such reserves, or supported the one Dr. Charles F. Holder fought for in 1913, there is no doubt in my mind we would have more abundant fish and invertebrate populations here today. Please give thought to the future, rather than the short-term present, when giving thought to this important issue.

© 2009 Dr. Bill Bushing. Watch the "Dive Dry with Dr. Bill" underwater videos on Catalina Cable TV channel 49, 10:00 AM and 5:00 PM weekdays and on Charter Communications Cable channel 33 at 7:30 PM on Tuesdays in the Riverside/Norco area. Please help me climb out of self-imposed poverty... buy my DVD's (see this link). Yes, take Dr. Bill home with you... we'll both be glad you did!

External Proposal C, an example of a marine reserve design which does offer good, scientifically-based placement
of reserves... with the exception of its extension out to the 3-mile limit which is unfair to the fishing community.

This document maintained by Dr. Bill Bushing.
Material and images © 2008 Star Thrower Educational Multimedia