This past Thursday, Nick Legler, a DNR Great Lakes Fisheries Management Biologist, came in to talk with us about Chinook salmon management in Lake Michigan. Chinook salmon are not native to the Great Lakes, but once the alewife population skyrocketed, different trout and salmon species were brought in to control them. Chinook and alewife are both pelagic feeders, and therefore Chinook did the best in controlling alewife populations. This worked great for a while, but now there are too many predator fish and not enough prey, which causes a lack of nutrition for the salmon.
Many forage surveys were completed, and results show that overall forage biomass is very low – the alewives aren’t reaching their typical size, and the salmon are consuming them at a younger age than normal (1-3 years). This proves to be more energetically costly for the salmon. Since quagga and zebra mussels have moved in, they have removed a lot of the smaller organisms that larval alewife usually eat, causing food shortages for them. This factor, along with the large number of Chinook salmon in the lake, is causing a top-down bottom-up effect and putting too much pressure on the alewife to survive.
Chinook salmon are currently raised in a number of hatcheries in the state that prove to be successful. However, reduced stocking of these fish may be needed in order to get the alewife population back up. It would be pointless to stock even more Chinook salmon, because without a main food source, they would not have a high survival rate.
On Thursday, March 26th, Kevin Mann came in to talk with us about Lake Sturgeon Streamside Rearing operations. Kevin is a fish biologist with the US Fish & Wildlife Service, and he works out of the Green Bay Fish and Wildlife Conservation Office.
Lake sturgeon are a very long-lived species and don’t mature until they are ~ 12-20 years old. Because of this factor, their populations do not increase too rapidly. Therefore, outside factors have a highly negative effect on them. Pollution, dam blockage and overfishing have all led to the extirpation of many populations. Some agreed upon solutions include: create fishing restrictions/closures, keep water flow relatively constant below dams, and regulate river pollution. Another big way to have a strong positive affect is to engage in streamside rearing.
Streamside rearing is done from a mobile trailer that ‘raises’ the sturgeon within the water of the river they will likely return to. Lake sturgeon are a species of fish that use natal homing to return to the river they were raised in to spawn, so this is a crucial part of the process. Before the water enters the tank, it is filtered to remove sediment and then UV treated to removed bacteria. This is done to protect the fish from starvation and disease. To obtain the gametes needed for reproduction, there are two methods. For populations being re-established, they take eggs and sperm from the fish. For populations that are being supplemented, they use ‘egg mats’ that collect the eggs, and bring those into the facility to raise. They also collect larval sturgeon during drift periods. Once the fish reach a size of 6-10 inches, they are tagged – either with a coded wire tage or PIT tag – and released.
On Thursday, March 12th, we had Tim Strakosh in from the US Fish and Wildlife Service to talk with us about their multi-state Lake Michigan Aquatic Invasive Species Early Detection Monitoring Program. Aquatic invasive species have huge ecological and economical impacts wherever they are prevalent. Loss of biodiversity, negative alterations to ecosystem functions, and increased climate change impacts are just a few, not to mention nearly $5.6 billion/year loss in commercial fisheries and $4.5 billion/year loss in sport fisheries in the Great Lakes area. The best resolution is to stop the invasives at the source of entry by first eliminating the inlet channels, then practicing early detection methods, and finally monitoring the ecosystem as a whole.
2014 was the first year this program was fully implemented. The success of the program largely depends on rapid communication with all partners involved, research, and constant outreach and education to the public. Tim is currently working on a risk assessment model to narrow the program and hopefully become more efficient.
Another large part of the AIS program is the e DNA surveillance, currently focused on bighead and silver carp populations. In 2013, there were 1,600 e DNA sample collected in the Great Lakes. By the following year, 2,150 samples were taken just from Lake Michigan, with 4,262 overall. Environmental DNA can be transferred through different vectors, like bird poop or barge ballast water, so that can give false positives. In these cases, extensive sampling would be done over multiple days to ensure the reading.
The AIS program also focuses on macro invertebrate sampling to screen for new mussels and/or amphipods, ichthyoplankton sampling, and nearshore sampling using traditional gear.
This week, we had Steve Fajfer from the WI DNR Wild Rose Hatchery in to talk with us about the role of fish propagation in fisheries management. Steve is the hatchery supervisor, and he has worked for the DNR most of his life – between 30 and 40 years. He was involved in a huge renovation project of the hatchery which took about 20 years to complete. The hatchery now regularly raises the following species: walleye, northern pike, musky, lake sturgeon, brown trout, Coho & Chinook salmon, and occasionally a few others. Wild Rose is the only hatchery in Wisconsin to raise lake sturgeon. The hatchery consists of different types of tanks to accommodate the habitat needs of each fish, such as netted cool & cold water ponds and indoor raceways. All the funding for the hatchery and its employees comes from fishing license sales, which is pretty neat.
The entire process of raising fish is pretty complicated. Once the eggs are extracted, they are incubated in separate compartments. Millions of eggs are sort through by hand, separating live from dead eggs. Eggs are treated with iodine beforehand to disinfect and minimize pathogens. Different water systems accompany the fish as they grow. For example, they use recirculating water and a heater system for the coolwater fish, and simple gravity flow for coldwater fish. When the fish are moved to outdoor ponds, they are fed minnows so that they grow faster. However, this type of harvest is labor intensive and minnows are vectors for many diseases, so this may also harm the fish. Species are released into lakes and streams at various times depending on their ideal stock size. This is a pretty broad outline of the process, and it is important nothing goes wrong – fish are seasonal breeders, meaning they can’t ‘start over’ with a year class if it isn’t raised properly.
Last week Thursday, Steve Stoinski came to talk with us about his career as a special agent working with through US Fish and Wildlife Service. Steve spent time working in a few different states (Alaska, Utah, Colorado) before landing the job that he has now. He has held positions as a legislative coordinator, field training officer and pilot, as well as his current position as a conservation warden.
As a special agent, Steve is responsible for coordinating efforts with foreign, state, and tribal governments, providing investigative training and educational programs, responding to natural disasters (Hurricane Katrina, BP oil spill), and last but not least, enforcing federal laws. One of the big ones is the Lacey Act, which gives him inter-state and foreign commerce enforcement ability. Under this act, Steve has worked undercover to take down illegal operations involving various wildlife hunting and/or poaching (deer, bear, mountain lion, etc.). The Marine Mammal Act is another that authorizes indigenous/native people to hunt marine mammals, but only if it’s subsistence hunting. Some of the other Acts he has worked in the name of include the Endangered Species Act, Bald and Golden Eagle Protection Act, Airborne Hunting Act, Migratory Bird Treaty Act, and a few Multinational Species Conservation Acts. Last summer, Steve was asked to help with an international training session in Botswana, Africa. He went over to help investigate elephant and rhino poachers, and he taught the participants how to catch poachers and how to work with others to best maximize their efforts. Steve’s talk was highly informative and very educational. It is good for us students to get a broader perspective on wildlife and our natural resources, especially those of us wanting to work in the field some day.
This past Thursday, Dave Boyarski came in to talk with us about commercial fisheries and management on Lake Michigan. Dave works for the Sturgeon Bay DNR as a fisheries supervisor. He briefly went over some history of commercial fishing operations in Lake Michigan. Historically, lake trout and burbot were the dominant predators in Lake Michigan, along with many near shore fish communities, cisco and lake whitefish populations. Today, we have a huge alewife population that makes up a large part of the fishery, as well as sea lampreys and many other invasive species. In effect, tributaries and near shore wetlands have become polluted and degraded, with drastic effects on the fish communities.
Currently, the Lake Michigan commercial fishery for yellow perch is closed and the sports fishery is limited due to declining populations. Part of the reason for this is sharp decreases in smaller-sized zooplankton and increases in the larger zooplankton, of which larval yellow perch are unable to consume. Other species, like the bloater chub (deep water cisco species) and rainbow smelt and experiencing reduced rates due to population declines. One species that is keeping the Lake MI fishery rolling is the lake whitefish. Most of these fish are successfully caught by trap nets or gill nets. It is very easy to overharvest fish, and in the case of the lake whitefish, it seems they have a handle on sustainability. There are highly detailed fishing quotas and regulations put in place to monitor the fishery in order to maintain this sustainability and prevent overharvesting. To do so, public involvement is a key part of the process. There are fishery boards, fishing forums, rule making and hearing processes, and a few more informal processes. During the rule-development stage, the public has a chance to comment on the economic impacts of these proposed changes. The public holds a lot of weight in determining which direction the decision is made in. Please visit the following webpage for more information on these events: http://dnr.wi.gov/topic/Fishing/lakemichigan/LakeMichiganFisheriesForum.html