2007 Fish Research Projects

Field

Side-Scan Sonar for Prediction of Rockfish Habitat
The Fish Research team started employing side-scan sonar in 2007. The method is used to visualize shoreline seabed features. From the images of nearshore seabed, together with verification dive surveys conducted in 2007, staff can predict which areas should be suitable for supporting inshore rockfish. The technique functions to 150 feet depth, but is most easily interpreted along the shoreline in shallower depths of 60 feet or less. Ideally, a grant funded project can be designed to map a significant proportion of the Howe Sound shoreline. The information gathered will provide a projection of the population density of shallow-dwelling rockfish for the entire region . By identifying and verifying with scuba dives the areas of highest abundance, the entire population of Howe Sound rockfish can be estimated through time as an adjunct to various conservation measures, such as the current ban on sportfishing for rockfish and lingcod in Howe Sound and the establishment of total hook-and-line closures like Rockfish Conservation Areas. Enforcement is the key to groundfish recovery everywhere in BC.

Rockfish Winter Hiding
Added to the ongoing rockfish abundance counts was a further category of whether the observed fish were found “inside” or “outside” of their chosen rock-pile habitat. Those found out in the open (where they would be visible on a videotape transect) were scored as being “outside” whereas those hiding under rocks were scored as being “inside.” Interestingly, sites where rockfish have been observed to be overwhelmingly “outside” during summer months were entirely “inside” during winter months. These results were observed for copper rockfish in shallow, shoreline rock piles. The results indicate that the fish are not migrating into deep water for the winter period, but instead hide deep in the safety of the rock pile. Now all dives conducted record the status of “in” or “out” for each rockfish counted.

Rocky Start to Citizen Rockfish Survey

With over a decade of successful participation by volunteer scuba divers in the annual Lingcod Egg Mass Survey, it was a surprise in 2007 to witness the virtual failure of public participation in the Rockfish Abundance Survey (RAS). Launched on-line in 2006, the RAS was promoted as something that could be undertaken any time during the year. Instructions for identifying the different shoreline rockfish species were provided on-line. Discussions with dive clubs and dive resort operators have revealed a number of possible reasons why divers are reluctant to attempt the RAS during their sport dives. One reason may be that the lack of an advertised time period to perform the survey in left divers unmotivated. This theory will be investigated by promoting the period before Labor Day as the season for RAS diving. It has also been suggested that divers are not confident about committing themselves to claiming to have correctly identified species and life stages. Finally, it could be that the lingcod counts can be accomplished during the course of an enjoyable sight-seeing dive, whereas counting rockfish could take over the entire dive. Ultimately, these questions will need to be resolved and the Aquarium will have to succeed in promoting this RAS diving so that citizen science can be deployed for monitoring abundance of rockfish in BC. Citizens are relied on because there will never be enough taxpayer dollars to fund the monitoring of BC’s 164 Rockfish Conservation Areas.

Annual Lingcod Egg Mass Survey
The 14th annual Lingcod Egg Mass Survey took place in February of 2007. This years survey showed that the overall abundance of lingcod spawning in Howe Sound remains at a level comparable to that in 2000-2005 (4.94 masses per hour, versus 4.7-6.5/hour), but less than the 9.11 masses per hour recorded in 2006. It is still an improvement over the range of 2.5-3.7 masses per hour in 1994-1998. Nonetheless, the spawners appear to remain young in Howe Sound.

Howe Sound Sponge Monitoring

Aquarium staff continued to monitor and photograph tagged boot sponges in Howe Sound. Cloud sponges, a species of glass sponge usually found in deep cold waters, occur here at the shallowest depths known outside of Antarctica, and are accessible to SCUBA divers. Cloud sponges can grow on rocky walls (cliffs) and are called “sponge gardens” or they can grow on top of the dead skeletons of other cloud sponges, which are a type of biologically generated reef called “bioherms.” We have found that the species diversity on bioherms is quite low compared to that of sponge gardens which are very diverse. It had been thought that bioherms in deep water serve as a critical habitat for rockfish babies, however, we have concluded that only cloud sponges in a sponge garden provide a nursery for baby rockfish.

Juvenile Spot Prawn Abundance Monitoring
Aquarium staff continued with their SCUBA counts of juvenile spot prawns in their nursery habitat under large bladed algae. In conjunction with new survey areas for Rockfish Conservation Areas, it was realized that juvenile prawn abundance can vary quite widely between areas that are relatively close, for example, Pam Rocks versus Finisterre Islet. This observation suggests the possibility that prawn larvae may resist drifting with currents away from their hatching site, a prospect that would affect management considerations for prawn fisheries. Prawns are managed in relatively large areas, as with all of Howe Sound.

North Pacific Marine Science Organization in Victoria
Jeff Marliave and Donna Gibbs authored a presentation given to the 16th annual PICES conference held in Victoria, October 26 - November 5. Scientists from across the Pacific Rim discussed the changing North Pacific Ocean at this very large gathering. Videos, photomurals and graphic representations of taxonomic biodiversity were presented by Jeff to explain the difference between rockfish survival in cloud sponges on rocky habitat (sponge gardens) or on reefs entirely of sponge (bioherms).

Georgia Basin Puget Sound Research Conference
Jeff Marliave and Wendell Challenger gave a presentation on predicting optimal rockfish habitat at the 2007 conference for transboundary collaboration toward marine conservation, hosted by Washington State and Environment Canada. Rockfish Conservation Areas (RCAs) in British Columbia were based on federal modeling that incorporated historical catch data and bathymetry information to predict optimal areas for designations. The macro-scale modeling approach fails to incorporate that rockfish often have very specific, small-scale habitat requirements. To address this concern a different approach was used in Howe Sound with a micro-scale habitat model to predict the probability of occupancy based on habitat types important to rockfish. A series of randomly selected dive sites inside versus outside the RCA prediction model were monitored on 69 dives in 2006. The new site-occupancy model demonstrated that rockfish occur in abundance both inside and outside the RCAs, but in very small hotspots according to habitat.

Lab

“Windows On Research” Display Sheds Light on Research Projects
The “Windows on Research” area in the new Canaccord Exploration Gallery has been redesigned to better engage visitors. These display tanks give the public a glimpse into current fish research projects, both in the lab and in the field. Larval fish rearing conducted in the lab is highlighted in the display tanks whereas interpretive delivery combined with movie clips highlight field work such as the Lingcod Egg Mass and Rockfish Abundance surveys.

Dietary Immunostimulation of Chum Salmon
Experimental trials were conducted in an attempt to determine the efficacy of introducing a mushroom immunostimulant into test diets and its subsequent effect on sea lice infection resistance in chum salmon. The sea lice infectious stages were provided by Dr. Kevin Butterworth of the UBC/DFO West Vancouver Laboratory.

Ninth Generation of Tubesnouts
Line-breeding of tubesnouts continued with the ninth generation born in the summer of 2007. Despite repeated inbreeding, only a few of the ninth generation hatches showed signs of abnormalities. This strong resistance to inbreeding depression is thought to result from their life-history characteristic of no planktonic drift as larvae. For animals which regularly have opportunities to mate with siblings, the species typically has eliminated bad gene combinations through survival of the fittest. Other species bred at the Aquarium, such as the sailfin sculpin, for which larval drift dispersal is very extensive, tend to suffer from inbreeding depression within a few generations.

Line-Breeding of Sailfin Sculpins
Reports on multiple generation propagation of tubesnouts has included discussion of inbreeding risks. The tubesnout project was started as a predicted basis for comparison with sailfin sculpins, a species which exhibited lethal inbreeding in eggs of third generation (F3) fish at the Aquarium. The hypothesized explanation is that larval drift is very extensive in sailfins, so that recessive genes might be masked by outcrossing with unrelated fish in nature. Tubesnouts have almost no larval drift, so they are not expected to suffer from back-crosses (inbreeding). In 2007 the Fish Research lab acquired two different sets of wild-caught, adult sailfin sculpins. The offspring from these two lines have been exhibited in the Windows on Research display so the public can admire their butterfly-like behavior. The two genetic lines are to be held separately and line-bred through successive generations. DNA fingerprinting will be employed to document divergence from wild-types as the fish pass through successive generations.

2007 Larval Fish Rearing
Continued success was met in 2007 with the culture of standard display species like grunt sculpins, tubesnouts, sailfin sculpins and spiny lumpsuckers. Various other species were attempted with less success. Most significantly, an attempt to culture quillback rockfish (Sebastes maliger) from a display pregnancy achieved only partial success. Quillback rockfish are closely related to China rockfish and copper rockfish, species cultured in 1999 and 2006, respectively. Only a relatively small number of larval quillback were born in 2007, since “partial pregnancy” actually occurs in rockfish. Normally, a brood of rockfish born to a single female will have multiple paternity, but the Pacific Canada display at the Aquarium only has one sexually active male. A minor portion of the birth from the female was of well-developed larvae, but the remainder of the birth consisted of unfertilized eggs. As a result, few larvae survived through to the final stages of larval development. However, a series of developmental stages was preserved, thus larval development in the three species can be investigated on a comparative basis. View a complete list of species reared in the fish lab.

HSRCG 2008 Fish Research Staff

Dr. Jeff Marliave - VP Marine Science
Kevin Kaufman, M.Sc. - Research Diver/Data Analyst (partial support from HSRCG)
Donna Gibbs - Research Diver/Taxonomist (partial support from HSRCG)
Conor McCracken - Research Diver (partial support from HSRCG)
Thomas Egli - Research Diver (partial support from HSRCG)
Zhen Hong Luo - Laboratory Coordinator
Justin Lisaingo - SFU Student Technician (full support from HSRCG)