Featured Scientist

Travis Tanaka on a boat sampling “slime eels”


Travis holding a California Halibut

Travis Tanaka is an environmental scientist with nearly two decades of experience working for CDFW. As a marine scientist with the Marine Region based out of the Monterey office, his primary responsibilities include monitoring the California halibut and Pacific hagfish fisheries, as well as collecting data to help manage their take.

Where did you grow up?

Paso Robles. Growing up in Paso really didn’t influence my future with CDFW or my choice to be a consumptive outdoor enthusiast. My influences came from my father and grandfather. My father taught me to be a hunter and responsible gun owner at a young age. My grandfather was a commercial fisherman and introduced me to fishing for various groundfish species. He taught me to appreciate our ocean’s resources.

What led you to a career in marine biology?

While going through school, I wanted to pursue a career in wildlife management or resource law enforcement. However, my path changed following a college lecture where the professor spoke candidly about upcoming job market opportunities and the future of what we might expect regarding job pursuits within the field of wildlife management. He said the reality was that we would find a lack of work in wildlife management, but that there would be upcoming needs in marine science. After that I began taking extra coursework in marine science and fisheries. Since I’d grown up fishing with my grandfather, I already had a vested interest in fisheries and so taking additional coursework was easy. I had to rethink my interest in resource law once I realized I wouldn’t be able to pass the vision exam.

Tell us about your current research.

I am a staff member on the Northern/Central California Finfish Research and Management Project where we monitor and conduct research on state-managed Finfish species (e.g. California halibut, surf perch, smelt and Pacific hagfish.) My role is to work on California halibut and Pacific hagfish.

For halibut, I monitor the fishery within Monterey Bay. This includes sampling the Monterey area commercial hook-and-line fishery for length distribution and age composition. Early on, I used to go to recreational launch sites and sample the halibut catch from sport anglers. The California Recreational Fisheries Survey (CRFS) program has a great handle on the recreational fishery now, so I put my focus on the commercial end. I also lead the processing for all halibut otoliths our project collects through sampling for ageing. Otoliths, also known as ear bones, are a hard, bony structure important to the fish’s sensory system. Each year, the fish will add a layer, similar to tree rings. I am one of two readers of all halibut otoliths sampled by CDFW staff. To date, we have aged 4,000 California halibut. This age-at-length dataset is one of several datasets that were incorporated into our latest stock assessment. Our project has been collecting halibut data since 2007.

In 2008, I began sampling the hagfish fishery out of Moss Landing to monitor and increase our knowledge of this remerging fishery. I developed a count-per-pound metric to sample live hagfish at the dock. Live hagfish are impossible to measure due to their movement and slime production. Hagfish can’t be sexed externally. To get an estimate of average weight or size, we randomly fill a bucket with hagfish, weigh the bucket and then count back the contents. If this is done repeatedly throughout the tank, we can develop an estimate for average weight. If the average count number goes up, then the fish are smaller per count, and vice versa. The ideal count is around four fish per pound, based on market demand. We then document the average size of retained hagfish and collect life history information, as well as information on the market and its participants.

During a short period in the early 1990s, the Pacific hagfish fishery in California flourished to satisfy an export market for hagfish skins where they were used to create expensive leather-like products, such as boots, bags, wallets and purses. However, a market-induced crash later occurred, and the fishery went dormant. But by 2007, a renewed market demand emerged for the harvest of live hagfish for use as human food.

Part of my job also involves working with fishermen interested in designing new harvest gear. Recently, I worked with fishermen who wanted to use barrels as a new trap type for the take of hagfish. After the fishermen secured experimental gear permits, our project evaluated their new gear design. With assistance from a colleague, we performed the necessary observation trips to collect data on interactions and bycatch. At the same time, we also collected lab samples to document sex ratios and the spawning maturity of hagfish caught by these traps. Once all of the results were in, we approved their new trap type that will improve quality-of-catch, reduce the number of traps on the seafloor, and ultimately be a viable option to existing trap gear.

What are Pacific hagfish?

Pacific hagfish are primitive, spineless, deep-sea fish that lack jaws, true eyes or a stomach. They live in muddy sea floors. Hagfish dine by scavenging dead or dying fish and marine mammals. They enter their prey through any existing hole or orifice they can find, or by creating a new hole via their two pairs of rasping jaws. Once inside, they tear the flesh from the carcasses as they devour their prey from the inside out. When stressed, their defensive mechanism is to overwhelm any prospective predators by exuding a thick viscous slime. This behavior is the reason hagfish are commonly called “slime eels.” Today, Pacific hagfish are caught and sold for human food, and much of the harvest is shipped to markets overseas.

What is a typical day like for you at work?

It depends on if my work day is during my field season or not. My halibut field season runs approximately May-October. Hagfish work is year-round but is significantly slower in the winter. During the field season, halibut sampling occurs in the morning and then I spend the afternoons in the office editing commercial fishing receipts, entering data, or processing halibut otoliths for ageing. Local hagfish sampling occurs in the morning. Once per month I travel to Morro Bay and Port San Luis to sample the Pacific hagfish fisheries in those ports. During the halibut off season, the average day is spent in the office working on the backlog of halibut otoliths, keeping up with landing receipt editing or addressing any pending issues. I spend a significant amount of time answering questions from commercial fishermen and recreational anglers.

What is the most challenging aspect of your job?

The most challenging aspect of the job, for me and for many others in CDFW, is balancing the needs of the resources (halibut and hagfish) with the needs of those people that use it. Within the group that utilize a fishery, there are often conflicts due to allocation between the recreational and commercial sectors (although not for hagfish, for which there is no recreational fishery). Thus, I am required to spend a significant amount of time answering questions from commercial fishermen and recreational anglers over a broad range of marine resources questions. As a CDFW environmental scientist, I must consider and balance the ramifications and consequences (biological, economic, social) of regulations and management actions.

Tell us something about yourself that many people would be surprised to learn.

It’s not really a surprise, but if I were not a CDFW scientist, I would be working as a commercial fishermen and hunting guide. I have also created some fishing tutorial videos on “Recreational Crabbing” and “Rockfish and Lingcod Fishing Tips and Tricks.” All are now posted on CDFW’s website and have nearly 40,000 views!

Media contact: Carrie Wilson, Communications, (831) 649-7191

Photos courtesy of Travis Tanaka. Top Photo: Travis sampling "slime eels".

Don Baldwin surveys rainbow trout at the headwaters of a small coastal stream in San Luis Obispo County. These wild trout serve as a seed population for coastal steelhead as some of their progeny may migrate out to the ocean.


Don conducts a snorkel survey on San Luis Obispo Creek.


Before he began monitoring steelhead in San Luis Obispo County, Don worked as a steelhead biologist in the Central Valley.


Don takes a summer hike to the summit of Mount Lassen to ski off the top.


A passionate backcountry skier, Don tours the Sierra through Yosemite National Park.

Don successfully completed CDFW’s Heritage Trout Challenge by catching six different native California trout in their historic range.

Don Baldwin is an environmental scientist with CDFWs Central Region based in San Luis Obispo. A 12-year CDFW employee, Don oversees the California Coastal Monitoring Program in the area and is tasked with surveying and assessing South Central California Coast steelhead, a threatened species listed under the federal Endangered Species Act. Steelhead are the anadromous population of rainbow trout that spend time in both the ocean and freshwater.

Born and raised in Sacramento, Don developed a love of trout and steelhead while growing up fishing the American River and small trout streams in the Sierra. His passion for steelhead in particular has influenced his education and career choices ever since. He holds a wildlife management degree from Humboldt State University – a school he chose in no small part due to its proximity to so many great north coast steelhead rivers.

When you think about some of the hallowed steelhead regions and waters of California, San Luis Obispo is not exactly top of the list. Can you explain the work you are doing there?

We are trying to get a grasp of what the wild steelhead population is in San Luis Obispo County. Since 2017, I have been implementing the California Coastal Monitoring Program there, which is part of our statewide responsibilities to monitor and recover these listed coastal salmon and steelhead populations under state and federal endangered species laws.
There are a lot of small, coastal streams in the county – approximately 25 plus their tributaries – and a lot of those are spring-fed with good, cold water with lots of wild rainbow trout in them. But not much research has been done so nobody really knows the population status of steelhead in the county.
Right now, I am looking for adult steelhead in the two priority coastal streams there – San Luis Obispo Creek and Santa Rosa Creek, the latter of which is in Cambria. We do that two ways: surveying for redds (fish nests) and using DIDSON sonar cameras to count the adults migrating upstream to spawn. We then build a mathematical relationship to estimate the number of adult steelhead for each redd we see. I am still in the preliminary stages of this monitoring program and have a way to go until we finalize our entire sample frame.

Are you finding many fish?

We did some redd surveys last year and we did find some redds, but never saw any adults while conducting spawner surveys. We’re still processing all the DIDSON data and have seen a few adult steelhead. I’m extremely optimistic we will see more. The last few years have been tough on steelhead in central and Southern California because of the drought, but they are a very resilient species. They have gone through this before. They’ve been around for thousands of years. They may have experienced droughts that have lasted 10, 20 years, but they keep coming back. So it’s exciting to be part of this project and monitoring these fish, yet it is challenging because they are so elusive and difficult to monitor. Hopefully, with these good rain events we are having this year, producing good flows, we will start seeing more fish.
What’s really special about this species is that there is this residence component of rainbow trout up in the headwaters of these streams that serves as a sort of seed bank for the anadromous component. They’ll just hang out and keep reproducing over the years and once the time is right, some of the juveniles may go out to the ocean.

Steelhead fishing opened on many coastal streams in December and January. Where would you direct steelhead anglers in San Luis Obispo County?

Go to the Eel River (in Humboldt County) (laughs). The streams in San Luis Obispo County are very small, some only a couple of miles long. Those that are open to fishing are open only in very small stretches on select days. You really need to read and understand the local fishing regulations. Many streams run through private property with no public access. There are just not a whole lot of fishing opportunities nor are there many fish.
To really immerse yourself in steelhead fishing and culture, go to the Eel River or Smith River (Del Norte County) and hire a guide with a drift boat. That’s how you have a chance to hook into a large chrome bright steelhead.

Can you explain the fascination with steelhead to somebody who’s never fished for them?

As a rainbow trout that goes to the ocean, they just get so much bigger, more powerful and strong. They are very elusive. You rarely see them. They return to freshwater, spawn, and then they are gone. Fishing for steelhead is like chasing ghosts, you always want to see what’s around the next corner.
They’re an absolutely beautiful fish. They fight hard and they’re exciting to catch. The appeal is the chase. When I first started steelhead fishing, I would go out for days and months and never catch anything. But I kept going back. I always heard it takes 300 hours of fishing before you start hooking them. And that’s pretty much it.

Anything surprising ever show up in these streams you are monitoring?

In San Luis Obispo County, we only have one species of salmonid: steelhead. We don’t have Chinook or coho salmon down there. The cool thing is that we have Pacific lamprey. Recently, that’s been the southernmost extent of their range. However, for about 10 years, we didn’t see any lamprey in San Luis Obispo Creek. They were nonexistent.
Down by the estuary there’s a saltwater intrusion weir with a fish ladder that wasn’t functioning well. A couple of years ago a “lamp ramp” was installed on the weir – which is a lamprey passage ramp made from a piece of curved sheet metal. Lamprey can’t scale a 90-degree angle as they use their mouths to suction-cup their way upstream over wetted obstacles. Ever since the lamp ramp was installed, we’re seeing adult lamprey, lamprey redds and a lot offspring once again in San Luis Obispo Creek.

Are lamprey a type of eel?

No. They look like an eel but don’t have paired fins or jaws like an eel. They are a completely different species. We don’t have freshwater eels on the West Coast. They have those on the East Coast. Adult lamprey have a round, sucker-like mouth and are parasitic when in the marine environment. They attach and feed on marine fish, including salmon and steelhead in the ocean.
Lamprey are a remarkably interesting species. They are an anadromous species like steelhead and salmon. They come into freshwater and hunker down in the gravel for a year without feeding. They absorb all their nutrients into developing their gonads and then come out a year later, dig a redd, spawn and die. They produce thousands of young that will live in the gravel for up to six, seven years. And they’re filter feeders, so they are aerating the stream bed and cleaning the water. Once they get to the size of about a pencil, they will migrate out to the ocean, grow up, and return one to three years later to spawn.

If you had free reign and unlimited funding, what scientific project would you most like to do?

I would be doing exactly what I’m doing right now and just really build a huge monitoring program. It really takes an army to do it well. You really must have multiple crews to go out and collect field data. You need a crew processing sonar data. You need a lot of equipment and sampling gear, especially when we start monitoring juvenile steelhead in the future. It takes a lot of people, equipment and money. Right now, it’s just me and a couple Watershed Stewards Program (WSP) members a day or two a week trying to do everything. So I would love to have free reign and staff and money to really monitor steelhead throughout San Luis Obispo County so we could really understand and tell their story and put this program on the map.

Tell us something about yourself many people would be surprised to learn.

I’m a ski bum. My true passion is backcountry skiing in the high Sierra and southern Cascade mountains. I started skiing when I was 5 and spent a lot of time in the mountains growing up. I don’t ski as much as I’d like to these days, but I still get out there a few times a year.

CDFW Photos. Top Photo: An avid fly fisherman, Don shows off a coastal cutthroat trout he caught in northern California before releasing it.