California Department of Fish and Wildlife

Mark-Recapture Study of Nearshore Groundfishes at Carmel Pinnacles State Marine Reserve

Background

In 1999, the California legislature passed the Marine Life Protection Act (MLPA) to help conserve biodiversity, protect habitat, and rebuild depleted fisheries. As part of the MLPA, in fall of 2007 a network of 29 marine protected areas (MPAs) was implemented along the central California coast between Pigeon Pt. and Pt. Conception. The MLPA calls for monitoring of selected areas to assist with adaptive management of the MPA network (see MLPA Master Plan).

Many of the central coast MPAs are currently being monitored or have been studied in the past; however, few data exist for the Carmel Pinnacles State Marine Reserve (Pinnacles). The purpose of this study is to collect baseline information on fish populations within Pinnacles and monitor changes over time to help evaluate the MPA's effectiveness. Located offshore at the north end of Carmel Bay, the site is characterized by high rocky relief areas, which form pinnacles separated by sand channels. While many of the newly adopted central coast MPAs have various levels of rocky habitat, few if any have as high a degree of variability as the Pinnacles site.

Sampling areas (red boxes) and bottom topography at Carmel Pinnacles State Marine Reserve and Carmel Point.  Rough areas represent higher relief and rocky habitat.
Sampling areas (red boxes) and bottom topography at Carmel Pinnacles State Marine Reserve and Carmel Point. Rough areas represent higher relief and rocky habitat.

Study Methods

From 2008 to 2010, data on nearshore groundfish abundances, sizes, catch rates, and movements inside this MPA and in a nearby reference site at Carmel Point were collected by California Department of Fish and Wildlife (CDFW) staff using mark and recapture (tagging) methods. Sampling was conducted during summer through early fall each year; typically July through September. Groundfish species of interest included lingcod, cabezon, kelp greenling and rockfish. Following capture, fish were measured, tagged and released.

Hook-and-line: Local sportfishing charter boats and a Monterey Bay National Marine Sanctuary research vessel were used to help catch and tag fish using rod and reel (hook-and-line) at Pinnacles and Carmel Point. Fishing occurred within two 500m x 500m grid cells at each site.

To engage the public as participants in the study, flyers were posted at boat ramps, tackle shops, and online to recruit experienced volunteer anglers to help catch fish. Three gear types were used equally to catch fish: shrimp flies, shrimp flies with bait, and bar jigs with a shrimp fly teaser. To reduce mortality, fishing was limited to depths less than 120 feet; similar depths were fished at both sites. Following capture, fish were measured, tagged, and released. Fish exhibiting excessive trauma or fish that were less than 20 cm total length were released without being tagged.

Shrimp fly and bar-jig gear used for hook-and-line sampling. CDFW photo by Scot Lucas.
Shrimp fly and bar-jig gear used for hook-and-line sampling. CDFW photo by Scot Lucas.

Trap: Commercial trap gear was used to catch "bottom associated" species. Trapping occurred within the same grid cells as above, but during different weeks than the hook-and-line fishing. Two sets of between 10 and 12 traps were fished in each of the four grid cells each of three months, during summer and early fall. Squid was used as bait and traps were pulled after soaking for about one hour (see photo below). To reduce mortality and facilitate trap retrieval, trapping was limited to depths less than 75 feet; similar depths were fished at both sites. Following capture, fish were measured, tagged, and released.

Commercial trap gear used to sample bottom associated 
species. CDFW photo by Diane Haas.
Commercial trap gear used to sample bottom associated species.
CDFW photo by Diane Haas.

Findings to Date

Catch and species composition

Over three sampling years, a total of 87 volunteer anglers using hook-and-line gear caught 3,449 fish, 2,878 of which were tagged. The catch was comprised of 18 different species. Overall, more fish were caught outside the MPA than were caught inside, although fish were typically larger inside the MPA. Black, blue, canary, copper, olive, vermilion and yellowtail rockfish were caught more frequently at Carmel Point, while gopher, china and kelp rockfish were more common at Pinnacles. All other species were caught in similar numbers or were too few in number to report on. Blue, gopher and olive rockfish were the most common fishes caught both inside and outside of the MPA.

To complement hook-and-line sampling, a total 745 traps were deployed yielding 1,237 caught fish, 1,156 of which were tagged over the three years. Twelve species were represented in the catch. Gopher rockfish, china rockfish, and cabezon were the most common species trapped at Pinnacles, while gopher rockfish, black-and-yellow rockfish and kelp greenling were the most common fish trapped at Carmel Point. Gopher rockfish was overwhelmingly the dominant fish caught at both sites making up 74% and 80% of the catch at Carmel Point and Pinnacles respectively, over the three year period. More fish were trapped inside the MPA than outside the MPA, and fish inside the MPA were typically larger than those caught at the reference site.

Species composition of fish caught by site and gear type in 2008-2010

Pinnacles Hook-and-Line | Pinnacles Trap | Carmel Hook-and-Line | Carmel Trap

Fish abundance

Relative abundance of individual fish species at each site was calculated as catch per unit of effort (CPUE). CPUE is listed in the tables below as the average number of fish caught per "angler-hour" (number of anglers multiplied by number of hours fished) for hook-and-line fishing, and as the average number of fish caught per "trap-hour" (number of traps multiplied by number of hours soaked) for trap fishing. These baseline relative abundances will be important in looking at trends in catch rates over time.

CPUE for hook-and-line and trap gear

Note: Dashes (--) indicate no fish were caught for that species.

2008 | 2009 | 2010 | All Years | All Species Combined

Fish lengths

Mean total lengths for 11 of the 14 most frequently caught species (gear types combined by site and year) were larger at Pinnacles than at Carmel Point in 2010. This is an increase in number of species from 2008, in which 8 of 14 common species were larger at Pinnacles than at Carmel Point. One species, canary rockfish, was common at Carmel Point but not caught at Pinnacles at all in the three years. Another species, black rockfish, was common at Carmel Point in 2008 but only one was caught at this site in 2010. Black rockfish were either rare (2008) or not encountered (2009, 2010) at Pinnacles over this period.

The smallest groundfish caught using hook-and-line were blue rockfish and yellowtail rockfish at 13 cm, and the largest was a 75 cm lingcod. For trap gear, the smallest groundfish caught was a 17 cm gopher rockfish and the largest was a 74 cm lingcod.

Average Total Length of Common Fish Caught Using Hook-and-Line and Trap Gear
combined at Carmel Pinnacles SMR (MPA) and Carmel Pt (REF) from 2008-2010

Average Total Length of Common Fish Caught

Information about the amount of mature-sized fish in a community is an important indicator of the overall health and stability of a population. Preliminary data from this study indicate that both black and yellowtail rockfish average total lengths were much smaller than the recognized length at 50% maturity, regardless of site. To a lesser extent, blue, copper, olive and vermilion rockfish average lengths, as well as lingcod, were also under the recognized length at 50% maturity for these species at both sites. All other species had average total lengths above the recognized size at 50% maturity.

Tag recaptures

To date, 59 tagged fish have been recaptured and released during CDFW sampling days; 20 tagged fish have been recaptured by the public (recreational/commercial fishermen and recreational divers); and 24 tagged fish have been visually "recaptured" by CDFW staff during scuba surveys (see photos below). One cabezon has been recaptured twice. So far, all fish have been recaptured in the same general area where they were originally tagged.

Tagged cabezon at Carmel Pinnacles State Marine Reserve, January 2009. Photo by Clinton Bauder.
Tagged cabezon at Carmel Pinnacles State Marine Reserve, January 2009. Photo by Clinton Bauder.

Tagged gopher rockfish at Carmel Pinnacles State Marine Reserve, January 2009. Photo by Jim Van Gogh.
Tagged gopher rockfish at Carmel Pinnacles State Marine Reserve, January 2009. Photo by Jim Van Gogh.

What to do if you catch a tagged fish

Each tag has a unique ID number and a CDFW phone number for anglers to call when they catch a tagged fish. Anglers are asked to provide the following information when reporting a tagged fish:

  • tag number
  • date caught
  • general location or GPS coordinates
  • total length (estimated or measured)
  • any additional information

Other Studies

Several non-CDFW studies are currently being conducted within the Carmel Bay area as well. One particular study by Rick Starr at Moss Landing Marine Laboratory also collects data on fishes using similar methods at Pt. Lobos State Marine Reserve (SMR). Closed to all fishing since 1973, data collected at Pt. Lobos SMR will provide a useful gauge with which to compare the nearby Pinnacles site as it is monitored over time.

More information can be found on the Sanctuary Integrated Monitoring Network website.