Final report for FNE23-056
Project Information
In 2023, we performed a study funded by Northeast SARE with Jersey Devil Oysters and Whale Point Oyster Farm with the purpose of testing 3 different bird deterrent methods during the growing season. Oyster farms attract all sorts of marine wildlife, which love all the wonderful places to live, feed, hide and thrive. In the same way that a reef is an underwater place for many species to thrive, so are the thousands of cages used in the rearing of oysters. As a result, birds love to land on oyster cages to rest their wings and possibly find lunch swimming about.
A recent decree from state and federal regulators requires that oyster farms find ways of deterring birds from landing on their gear. As the industry experiments with ways to fulfill this task, we decided we’d play our part.
Our study consisted of observing the effectiveness and cost of 3 types of bird deterrent methods
- Tactile (spikes installed on cages to prevent them from landing)
- Visual (kites that resemble Bald Eagles, the natural predator to the many bird species of the coastal zone
- Auditory (a speaker device which emulates the distress calls of the target bird species)
After a season of observing these 3 methods at three different farm sites on the Atlantic coast of New Jersey, the results were clear: bird spikes or the ‘tactile’ method of deterrent is a far superior method, despite the considerable nuisance of having sharp spikes on every cage we must service throughout the year to grow our product.
Birds, as it turns out, are quite smart and adaptable. It didn’t take long for them to become accustomed to the recorded sounds of their species under distress as well as the kite printed with an eagle on it.
Farmers of all types have had to contend with nature and specifically birds since humans first began to replace the spear with a hoe. Oyster farmers do not get a pass…but if nothing else, farmers are good at adapting to the conditions handed to them and finding a way.
Our project seeks to test three bird deterrent products which include: auditory (sonic bird repeller), tactile (spikes), and visual (hawk kite), measuring: effectiveness, cost, and durability.
Our project seeks to find the best bird deterrent product in all of the above categories, for oyster farms in our region to use for complying with the National Shellfish Sanitation Program’s Model Ordinance mandate.
Floating aquaculture gear provides a roosting site for shorebirds (ie. gulls, cormorants, terns, pelicans). Birds feed and defecate on the gear, resulting in the potential to contaminate the surrounding growing area and contribute to poor water quality on oyster farms (Barnes, 2019). This leads to a need for bird deterrent methods to decrease the amount of birds roosting on aquaculture gear and oysters that are grown for human consumption.
The National Shellfish Sanitation Program (NSSP) is the federal/state cooperative program recognized by the U.S. Food and Drug Administration (FDA) and the Interstate Shellfish Sanitation Conference (ISSC) for the sanitary control of shellfish produced and sold for human consumption. The NSSP revises its Model Ordinance (MO) every two years with input from regulators, scientists, federal agencies and industry. Each state must adopt the MO and implement it under their shellfish program, defining an authority. New Jersey’s defined authorities are the New Jersey Department of Environmental Protection’s (NJDEP), including NJDEP’s Bureaus of Shellfisheries, Marine Water Monitoring, and Law Enforcement, as well as the New Jersey Department of Health (NJDOH).
The most recent version of the MO involves the requirement for farmers that are using floating oyster gear to implement a bird management plan. Under the MO’s Shoreline Survey Requirements, the authority shall “consider the presence of domestic, wild animal or resident and migrating bird populations for possible adverse effects on growing areas” (Schuster, 2022). In response, the NJDEP mandated that all floating oyster gear users submit a “bird deterrent plan”. Following 2022 patrols, the authority sent letters to all aquaculture farmers stating: “It has come to the attention of the NJDEP that not all aquaculturists using floating gear are following the bird deterrent plans they have submitted to the Department. In addition, some of the submitted bird deterrent plans have been shown to be ineffective as birds have been observed actively roosting on the gear even with deterrents installed” (Schuster, 2022).
Two occurrences have caused this change in the MO:
The first is a recent illness that warranted an investigation in Rhode Island (Marler, 2021). The investigation yielded shellfish testing positive for campylobacter lori (Marler, 2021). According to the Centers for Disease Control and Prevention (CDC), people with Campylobacter infections usually have diarrhea (often bloody), fever, and stomach cramps, with occasional nausea and vomiting reported (CDC, 2021).
The second is an increase in floating gear being used within the industry. Oyster aquaculture is an intensive activity, where the primary cost is labor. The use of floating gear is less labor intensive than submerged, bottom cages. Floating gear also reduces predation that typically occurs on the bottom. Floating gear also facilitates faster oyster growth since phytoplankton, the primary food source for oysters, is more prevalent at the surface. The USDA’s Natural Resource Conservation Service (NRCS) has integrated oyster aquaculture into its Environmental Quality Incentive Program (EQIP), engaging with many farmers to switch their bottom growing methods to floating and ultimately allowing them to compete with standards within the broader coastal industry.
Terrestrial agriculture has always faced issues with the presence of birds. Many of the practices that might be considered effective for deterring birds in terrestrial agriculture wouldn’t be practical for oyster aquaculture that is conducted on shellfish leases and where public presence is permissible. The primary reason for a lack of “bird deterrent” compliance stated by farmers is that it’s cost prohibitive and there is fear that the methods still will not prohibit the presence of birds. The NJDEP has stated in the recent MO letter that “this issue is serious, and it will not be resolved unless the industry finds an effective way to deter birds from floating gear…it is possible that floating gear could be entirely prohibited in certain areas or possibly even Statewide” (Schuster, 2022).
Our project seeks to explore three different oyster farm bird deterrent methods, those being: auditory (sonic bird repeller), tactile (spikes), and visual (predator model such as a hawk kite). Our project aims to field test various off-the-shelf bird deterrent products measuring effectiveness, cost, and durability. The results of our project will directly benefit the increasing number of oyster farmers that utilize floating gear in New Jersey, as well as in other states. With an increased understanding of effective bird deterrent methods, this will reduce the health risks in oyster farming aquaculture caused by birds roosting on the crop and defecating, and improve productivity of oyster farms.
Barnegat Oyster Holdings, a shallow six acre site, surrounded by natural sedge islands in the Barnegat Bay, NJ. The nearby islands are seagull and tern nesting sites. Farmer Scott Lennox produces oysters full time. His primary growing methods involve planting oysters in floating cages which are finished in cages and trays. He started his career as a science teacher and since 2015 he has transitioned to farming full time. Barnegat Oyster Holdings gross sales are $1,300,000, selling primarily to retailers and regional wholesalers. Lennox plans to dedicate existing oysters, bags, cages, line, and anchors on his farm to the project, an in-kind contribution of $7,000.
Cooperators
- - Producer
- - Producer
- - Producer (Researcher)
- - Technical Advisor
Research
Methods and Materials as proposed
Materials:
- 9 cameras
- 3 hawk kites
- 360 bird spikes
- 3 auditory sound devices
- 3,600 feet of rope*
- 18 anchors*
- 90 floating 2-bay cages*
- 180 14mm mesh bags*
- 108,000 oysters*
- 18 12 foot galvanized poles*
- 500 zip ties*
* not included in budget, provided by farmers for normal farming operations
Overview:
Our project will field test three different bird deterrent devices on floating oyster cages at three different farm sites. Each deterrent will be considered for the following criteria: 1) effectiveness of eliminating bird presence on farming gear, 2) cost, both upfront as well as repair/maintenance and replacement, and 3) durability of the device to withstand the adverse conditions on open water oyster farms. Each device will be tested over a 2 month period during the growing season when birds are abundant.
Experimental bird deterrent products:
Three categories of devices have been selected based on the work by Rivadeneira et al.
- Tactile deterrents utilize a physical obstacle that a bird will encounter upon attempting to land on floating farm gear. For our project, we have selected stainless steel bird control spikes, which consist of rigid metal wire affixed to a steel strip and zip tied to each float on a cage.
- Visual deterrents can utilize the ‘scarecrow’ approach, creating a visual model (often of a predator) that would detract birds from foraging nearby. For our project, we have selected bird scaring hawk kites as a natural predator to the bird species present on area oyster farms, to be placed near the experimental floating cages.
- Auditory deterrents utilize sound, both sonic and ultrasonic, to bother and discourage foraging and roosting behavior. For our project, we have selected a sonic device that emulates distress calls from the target species as well as natural predator calls.
Experimental test sites:
Three active farming sites have been selected for our project, each utilizing floating cages where large populations of waterfowl are observed each growing season. The sites were selected based on their diverse locations along New Jersey’s Atlantic Coast. See Map 1 for a regional view of our three experimental sites.
Site 1) Barnegat Oyster Holdings Lease
This 6 acre active oyster farming lease has 800 floating cages, 500 floating bags and 400 bottom cages/trays. The site is 2.5’ depth at mean low water and has a range of bottom types, from sandy to firm and tacky.
Site 2) Whale Creek Oyster Farm - Whale Creek, Strathmere, NJ
This 2 acre site has 90 floating cages with other oyster farms in the same body of water. It has a soft muddy bottom. The site is 6’ deep at mean low water.
Site 3) Jersey Devil - Little Egg Harbor Township, Great Bay, NJ
This 2 acre site has 100 floating cages and has several nearby acres of extensive (bottom planted) oyster farms. It is 6’ at mean low water with a bottom that ranges from sandy to soft, depending on seasonality.
Experiment arrangement and timeline:
- Each testing site will have 3 longlines of 10 floating bags. Line A, Line B and Line C.
- This results in 9 longlines total between all of the experimental farms
- Each longline will be 100 feet apart and have its own camera at the top of the longline pole to observe bird presence at the same time and interval across lines and farming sites. (Only 9 cameras are needed for our project, however 1 extra camera has been added to the budget as a backup in the event of damage.)
- Our project must forgo the control group because we cannot obtain an approved research lease in time with floating aquaculture gear on it (typically takes ~ 2 years for research lease approval). It is crucial to get data on effective bird deterrent products, in order to comply with the recent DEP MO.
Testing for each deterrent method will run simultaneously at each site, as follows:
May-June: Tactile method using spikes on floating bags
July - August: Visual method using predator model hawk kite mounted at one end of the lease
September - October: Auditory method using sonic sound mounted at one end of the lease
Gear and bird deterrent methods and cameras will be obtained and deployed by May 1st, 2023, when birds usually start to appear on the farm - late April/May. Observations/data collection will occur through October 2023, when birds usually leave the farm to migrate and their presence is no longer an issue.
Observation criteria:
Each farm test site will use its own existing oyster growing gear and seed, carrying out normal farming activities while the study is ongoing.
Observation data will be collected based on the following categories:
- Effectiveness
- Cost
- Durability
Effectiveness:
Data will be collected every 3 days over the 2 month period for each device. Remote cameras affixed to pilings at each longline will allow for observations to be made simultaneously at each long line and at each site. A rotation of times will be used to observe birds at different times of day. Between 8-9am, 12-1pm, and 5-6pm.
For the visual and auditory methods, effectiveness at different longline distances from the hawk kite and sonic devices will be measured across longlines A, B, and C.
Cost & durability:
A journal of each occurrence needing either maintenance, repair, or replacement will be kept during the entirety of the study. Each occurrence will be recorded with the cost in both hours and materials. See Table 3 for a data collection journal example.
Analysis:
Upon completion of the study of each device across the 3 sites, the following will be used to analyze the practicality for use on floating cage oyster farms needing to mitigate the presence of birds. Potential conclusions range from a successful test of an individual device that fits the effectiveness, cost, and durability needs of a farm to the need for the study of more devices in order to find a practical solution.
Effectiveness will be measured by the device's ability to remove all foraging or roosting behavior of birds on floating gear. An average of less than 1 bird observed per location at each moment of observation will be considered effective. For the visual and auditory methods, effectiveness at different longline distances from the hawk kite and sonic devices will be measured and compared.
Total cost will be calculated upon completion of the 2 month study of each device. Material costs will be added to labor costs to determine a grand total. Costs will be compared with the other experimental device totals.
An analysis of the occurrences in the journal requiring attention will be used to determine the durability. Environmental conditions as well as the ability of the device to withstand the effects of normal farming activities being performed on the gear (harvesting, flipping cages, etc) could all affect the durability of the device, with each occurrence recorded in the journal.
May-June: Tactile method using spikes on floating bags
Installation & Maintenance:
|
Action |
Average Labor Hours (x $20) |
Installation/Replacement/repair cost |
Total Average Cost |
|
Installation |
10 hours |
$1,798.80 |
$1,998.80 |
|
Repairs |
2 hours |
$0 |
$40 |
Data Collection Analysis:
While birds were observed in other areas of the farms (on floating work platforms, cages without spikes, larger buoys and corner stakes), very few birds were observed on any of the cages. Only on rare occasions were Foster’s Terns observed perched on areas where a bird spike shifted off of the center area of a cage float.
*Camera’s were too inconsistent in their ability to detect bird motion in the designated test area. As a result, all data collection was done when the farm crew arrived at the test site each Monday, Wednesday & Friday.
Effectiveness
Bird spikes, once installed had a high effectiveness, with only a few instances of birds being able to roost on cages.
Cost
$2,038.80
Durability
Overall, the bird spikes had a high durability during the testing period on all farm sites. The bird spike product used was not designed to be installed on oyster cages and therefore, the spikes had to be adjusted over the course of the testing period from wear and tear of flipping and servicing oysters in the cages, with a total estimated average 2 hours of labor.
July-August: Visual method using predator model hawk kite mounted at one end of the lease
Installation & Maintenance:
|
Action |
Average Labor Hours (x $20) |
Installation/Replacement/repair cost |
Total Average Cost |
|
Installation |
1 |
$50 |
$70 |
|
Repairs |
3 |
0 |
$60 |
|
Replacement |
2 |
$100 |
$140 |
Data Collection Analysis:
Bird presence in the hawk kite area was initially observed to be minimal at each farm site, especially in the cages in close proximity to the kite. Early observations were promising, as the birds present on other parts of the farm sites didn’t seem to be interested in the area immediately adjacent to the kites. However, after the first week, roosting seemed to spread to all cages in the test area at each farm site, even those close to the device. Additionally, the kites were susceptible to damage and destruction after any prolonged weather event, such as a thunderstorm or strong winds. Repair and replacement was frequent.
*Camera’s were too inconsistent in their ability to detect bird motion in the designated test area. As a result, all data collection was done when the farm crew arrived at the test site each Monday, Wednesday & Friday.
Effectiveness
Effectiveness was found to be minimal over the course of the testing period.
Cost
$270
Durability
Poor
September-October: Auditory method using sonic sound mounted at one end of the lease
Installation & Maintenance:
|
Action |
Average Labor Hours (x $20) |
Installation/Replacement/repair cost |
Total Average Cost |
|
Installation |
8 |
$3,952.03 |
$4,112.03 |
Data Collection Analysis:
Similar to the kite deterrent, the sound blasters were observed to have a period of effectiveness for the first few week period of operation at each farm site. Birds were found to be less prevalent in the testing areas, as well as some of the sections of the farms adjacent to the testing areas. Certain species were observed to be congregating in the further reaches of the farm (in the case of the Barnegat Light farm site), far from the sound device (Brown Pelicans, Fosters Terns), while others were observed in the testing area, but at lower populations than elsewhere (Gulls, Cormorants). After week two of the testing period however, observation data appeared to point to the fact that the birds were becoming accustomed to the sounds and were no longer deterred. By the second month, birds such as Herring Gulls were observed perched atop of the speaker tower, completely unphased by the sounds.
*Camera’s were too inconsistent in their ability to detect bird motion in the designated test area. As a result, all data collection was done when the farm crew arrived at the test site each Monday, Wednesday & Friday.
Effectiveness
Mild to poor
Cost
$4,112.03
Durability
High
Conclusions:
A recent amendment to the National Shellfish Sanitation Program’s Model Ordinance mandates aquaculturists to include “mitigation or deterrent measures to minimize the potential pollution impact of birds”.
Oyster farmers find themselves inundated with emails and phone calls from salespeople touting attractive solutions to this problem. Many of these options claim to solve the bird problem with devices that would not require any modification of farming gear, which comes with considerable nuisances to farmers, who have to install on all of their sometimes thousands of pieces of gear each spring and remove at the end of the growing season. Solutions like auditory devices seem like attractive solutions because they claim to rid acres of area of bird presence.
After our study and the decisive evidence against auditory solutions such as the one we used has resulted in farmers avoiding having to incur the expense of learning the hard way after purchasing the expensive and ineffective solution on their own.
Education & Outreach Activities and Participation Summary
Participation Summary:
Outreach consisted of a social media campaign to communicate the findings of the study as well as 2 meetings with the NJ aquaculture industry.
Our initial meeting was prior to deployment and data collection. It was in December 2022 with the NJ Aquaculture Association and presented as an agenda item during a meeting addressing the following growing season’s requirements passed down by the NJDEP from the FDA regarding the bird deterrent regulations that would be imposed on the industry. Our study was presented and comments given regarding the potential outcome.
The second was during the spring 2024 NJAA meeting, where the basic findings of deterrent method effectiveness was presented. As was the case with our operation, wishful thinking from many growers with respect to the effectiveness of methods such as the auditory and visual deterrents as an effective strategy were debunked. Growers commented on how they were thankful they hadn’t invested their money on expensive auditory devices or their time on relatively useless visual deterrents such as kites. It was the general consensus that bird spikes should be used by all and that it was important for all growers in areas with multiple farms present use this strategy to avoid the possibility of a downgraded water quality classification, which would affect everyone in a designated growing area.
Instagram Post/Fact Sheet
Learning Outcomes
- Tactile (spikes installed on cages to prevent them from landing)
- Visual (kites that resemble Bald Eagles, the natural predator to the many bird species of the coastal zone
- Auditory (a speaker device which emulates the distress calls of the target bird species)
After a season of observing tctile, visual and auditory methods of deterrence at three different farm sites on the Atlantic coast of New Jersey, the results were clear: bird spikes or the ‘tactile’ method of deterrent is a far superior method, despite the considerable nuisance of having sharp spikes on every cage we must service throughout the year to grow our product.
After our study and the decisive evidence against auditory solutions such as the one we used has resulted in farmers avoiding having to incur the expense of learning the hard way after purchasing the expensive and ineffective solution on their own.
Project Outcomes
The local industry as a whole has adopted bird spikes as their preferred solution to the bird presence on their farms. Although there were reports of warning letters being distributed by NJDEP to a few farms that were out of compliance after extensive farm inspections during the 2024 growing season, for the most part, the industry has satisfied the requirements and kept bird presence under their threshold.
Overall, the study was a good first step in identifying the best methods for farmers using floating cages and in need of deterring birds. Understanding how various deterrents work in a marine environment with challenging conditions is crucial to solving this ongoing issue. While auditory and visual deterrents may be effective, without further study, tactile deterrents currently appear to be the most practical short-term solution.
Several methodological lessons were learned. First, remote cameras were the most accurate tool for collecting data on bird presence at three sites, but the affordable cameras used fell short of the study's needs. Second, larger sites like Barnegat Light allowed for better comparison between areas with and without deterrents, which was useful for understanding their range and effectiveness. Larger sites should be considered for future studies focused on specific bird deterrents.
Further study of deterrent categories is needed. For instance, designing more durable, easily installable bird spikes would improve their efficiency. Testing ultrasonic auditory devices or other sounds may also be worthwhile. Additionally, exploring light-based deterrents, such as lasers or reflective installations, could expand our understanding of effective solutions.