Department of Natural Resources
The Michigan Fish Production System produces between 10-40 million fish each year for stocking statewide following the requirements provided by our Fisheries Managers for specific species, strains, sizes and numbers of fish to be placed at very specific locations and on certain dates. We have invested a significant amount of time and funds, nearly $1.7 million, into the unique vehicles that transport this multi-million dollar product from our hatcheries and rearing ponds (and also some out-of-state locations) to stock almost anywhere. The only unwritten "rules" of fish transportation are that the fish absolutely must be delivered alive and in stocking condition.
A fisheries management units transport fish also. These unit operations, although a smaller part of the fish production system, use trailer-based stocking units better suited to the production capacity of their coolwater (mostly walleye) rearing operations (Figure 1).
Pickup Truck with Various Trailer Mounted Fish Stocking Units
The current hatchery-based vehicle fleet is comprised of 18 stocking units based at the six state fish hatcheries. The vehicles range in tank capacity from 300 to 3,200 gallons. The smallest stocking unit is a 300 gallon tank mounted on a pick-up truck chassis. This unit is equipped with four-wheel-drive as well. The three 100 gallon tanks were specifically designed for off-road brook trout stocking primarily in Michigan's Upper Peninsula (Figure 2). The brook trout unit, like the other 17 stocking units in the fleet, is thermally insulated with two inches of polyurethane foam. The foam insulation is essential to minimize thermal transfer between ambient air temperatures and the transporting tank water. The tank insulation is theoretically designed to allow no more than a seven degree rise in tank temperature over an eight hour period.
Three by 100 Gallon Brook Trout Stocking Unit: SV-1040
Three by 250 Gallon Manchester Stocking Unit: SV-1340
The last 750 gallon Manchester Stocking Unit SV1340 (Figure 3) in Fisheries Division is housed at the Marquette State Fish Hatchery and is the next largest stocking unit in the fleet. Due to limited need for this three by 250 gallon vehicle it, like SV-1040, is used primarily for Upper Peninsula brook trout stocking. As the transportation cost per mile continues to rise, the demand for more efficient larger capacity transport units has increased and conversely the requests for smaller specialized units like SV-1340 have declined. As the vehicle fleet is modernized the emphasis will be to add larger capacity units while smaller units in this "class" will be phased out.
General Peterson Stocking Unit Information
1,200 Gallon Liquid Oxygen (L.O.X.) Equipped Stocking Unit: SV-1380
The 1,200 gallon "Peterson" stocking unit is considered the "standard" capacity vehicle and is equipped with four separate 300 gallon tanks (Figure 4). Currently, there are 10 Peterson Units in the vehicle fleet housed at five out of the six state fish hatchery facilities. SV-1380 (Figure 5) is a recently refurbished and upgraded unit. As the cost of fish stocking trucks has increased, the Fish Transportation Unit (within the Fish Production System) has initiated a program of refurbishing, upgrading and re-fitting existing old stocking tanks onto new truck chassis'. The refurbishing process has been highly successful at reducing monthly lease costs on what are essentially new units equipped with an upgraded liquid oxygen life support system.
Each upgraded Peterson unit is re-fitted with a low pressure 200 liter liquid oxygen tank capable of providing life support for an entire stocking season on a single filling. This large capacity system is a significant advance over the previous high pressure, but low capacity cylinder based system that contained oxygen for at most two days. Additionally, the liquid oxygen system operates at a lower pressure (350 psi) as compared to the prior high pressure oxygen cylinder system (2,000 psi). The lower working pressure makes the liquid oxygen system more reliable, easier to maintain, and we have the ability to refill them from the large bulk liquid oxygen tanks located at our hatcheries. For these and practical reasons like eliminating cylinder inventory control problems, virtually eliminating back injuries associated with cylinder lifting and the elimination of cylinder rental fees, all new and refurbished stocking units are now equipped with liquid oxygen. Incorporating liquid oxygen has been a significant improvement in Michigan fish transportation.
Since fish transport and stocking in Michigan is a high profile activity of Fisheries Division, efforts have been made to promote the products of Fish Production System on the stocking trucks. Each of the 18 stocking units have been furnished with prominent colorful graphics and a "Fish for the Future" logo. These graphics have been positioned on the driver, passenger and rear sides of each vehicle unless insufficient flat surface area was available on the vehicle. Current fleet vehicle planning calls for each new or refurbished stocking unit tank to be furnished with the same collage (or an updated version) that highlights the Fish Production System.
2,000 Gallon four by 500 Gallon Intermediate Stocking Unit: SV-1405
The Fish Transportation Fleet has four 2,000 gallon units that are termed "intermediate" class stocking units. These larger capacity units are housed at the Marquette, Platte River and Wolf Lake State Fish Hatcheries. SV-1345 is the only single compartment intermediate unit in the fleet. This unit is the least flexible of the intermediate units because it can only make one, albeit large, plant of fish. This unit has been used primarily at the Platte River State Fish Hatchery stocking larger coho and Chinook salmon sites on the Great Lakes. In recent years, more effort has been made to use this unit at other facilities as a means of quickly reducing spring raceway densities at a time when it is most desired.
The remaining three intermediate stocking units are equipped with four individual 500 gallon compartments. SV-1405 (Figure 6) is our newest four compartment liquid oxygen intermediate that was recently added to the stocking fleet. The new intermediate, SV-1405, replaced a smaller Manchester unit and as a result has added significantly to fish transporting capacity. The remaining two intermediate units, SV-1356 and SV-1344, are older vehicles that will be refurbished in the near future. After refurbishing is complete, these two intermediate units will provide many additional years of service as updated liquid oxygen-equipped vehicles.
Semi-replacement one by 3,500 Gallon Stocking Unit: SV-1346 (Non-liquid oxygen)
The largest stocking vehicle in the transportation fleet has a single compartment tank with a 3,500 gallon capacity. SV-1346 (Figure 7) is 15-years-old and one of the older units in the fleet. This unit is scheduled for a total system refurbishing in the near future. In spite of its' age this unit continues to perform admirably due in large part to its' efficient design and operation. The water re-circulating system, in concert with the oxygen supply support system, is undoubtedly one of the very best in the fleet but this efficiency was not noticed for many years.
SV-1346 as originally designed was a tall unit and when filled to capacity it also had an uncomfortably high center of gravity. To fix this situation, the tank carrying capacity was permanently reduced twice in order to improve driving characteristics. Reducing the water tank water level consequently also lowered the unit's center of gravity and improved the vehicles driving characteristics. Post modification volume calculations estimate that the tank capacity was reduced by approximately 500 gallons from the original 3,500 gallon design. After a review of stocking records and discussion with our seasoned fleet drivers, it is doubtful the fish loading capacity was ever adjusted downward to 3,000 +/- gallons in response to the smaller carrying capacity. So, in spite of an approximate 500 gallon reduction in capacity, this unit has been and continues to be loaded as if it contained 3,500 gallons of water. To date there has been no obvious reductions in the quality of fish stocked that could be attributed to this significant reduction in tank water capacity.
Straight Truck four by 3,200 Gallon Stocking Unit: SV-1433
Experience in stocking fish with the semi-replacement (SV-1346), specifically and other units generally, has yielded some valuable practical information on future stocking unit design improvements. This experience has paid dividends and has been integrated into the design and construction of the most recent addition to our fleet SV-1433 (Figure 8). This new vehicle is a straight truck with a 3,200 gallon capacity and it is unlike any other unit currently on the road. SV-1433 replaces SV-1358 which was a 4,000 gallon semi-tractor and trailer style unit (Figure 9) and was retired after 20 years of service. SV-1433 has four individual 800 gallon compartments and its three interior bulkhead walls are equipped with water tight doors. Depending on door position, open or closed, the vehicle tank capacity can be configured into any one of eight possible variations. This option makes this vehicle very flexible and useable at all six state fish hatcheries without requiring any fish loading system changes.
Semi Tractor Trailer four by 4,000 Gallon Stocking Unit: SV-1358
SV-1433 is equipped with three inches of insulation; an inch more than the standard two inches found in the Fish Production System's other units. This extra insulation is intended to minimize the potentially harmful effects of warming tank water on extended length stocking trips.
The liquid oxygen life support/water recirculation system on SV-1433 is powered by two 220 volt electrical AC/DC generators. One is intended to be the operating unit while the second paired unit serves as a backup power source. Each of four electrical pumps, installed in the side storage compartments, have been equipped with a variable frequency drive (VFD). Controls for the VFD's are located in the vehicle cab. These variable motor drives allow water re-circulation speed to be varied up or down to a maximum rate of 80 gallons per minute (gpm). This allows for a complete 800 or 3,200 gallon recirculation exchange in 10 minutes.
Water recirculation and oxygen levels in the tanks are two critical pieces of information the driver must continuously monitor. Water flow meters and an oxygen pressure switch have been incorporated into a combined visual and audible alarm system on our newest unit. The display panel for this system is positioned on the driver's console where both of these life support system displays can be monitored easily and efficiently.
This same basic display layout has proven it's usefulness over time and is utilized in all of our stocking units. With a quick glance the driver can easily monitor both the oxygen and the water recirculation status in any compartment on the vehicle. This layout has saved many fish over the years because an alert driver can avert many potential problems by taking quick action.
The semi-replacement SV-1346 as constructed had a fairly high center of gravity. This created a minor stability issue with the truck that was addressed post construction by lowering the overflow level in the water tank. SV-1433 was designed and built with potential driving stability issues in mind. The 3,200 was built as wide as legally possible for maximum stability and the center of gravity was kept as low as was physically possible. Actual test stocking trips with this unit indicate it is very a stable vehicle in both loaded and unloaded conditions.
SV-1433 (3,200 gallon) was built to replace the transport capacity of SV-1358 (4,000 gallon) and it is largely unknown at this time if this goal has been realized. Two preliminary "upper maximum load" stocking trips were successfully made during the fall of 2011. The unit's capabilities will be tested in earnest in the spring of 2012. Results to this point have been very positive and point to a smaller, more efficient, large capacity unit that will fit a wide variety of stocking demands as required statewide.