Knobbed Whelk

Busycon carica

Knobbed Whelk
Photo credit: Joshua Davis on Flickr

Status

Endangered

Physical 

The Knobbed Whelk is the official state shell of New Jersey. Knobbed Whelks are large marine gastropods (snails) with spiral shells opening on the right side.  The outer shell is grayish white to tan, while the inner shell color ranges from light yellow to orange. Adults grow 5-9 inches in length. Females are larger than males; adults may start out as males and change into females as they get older, which would explain why females are generally larger.

Image by Joshua Davis on Flickr

 

Habitat

Knobbed Whelks live in tidal estuaries on the Atlantic coast from Massachusetts to Florida.  In the spring and fall, they live in shallow water or subtidal mud or sand flats.  During the temperature extremes of winter and summer, they move to deeper offshore water.

 

Feeding 

Knobbed Whelks are predators feeding on clams, oysters, and other bivalves. They use their strong foot to move along the bottom of the bay as they search for food.  A Knobbed Whelk uses its foot to hold its prey and its shell edge to pry open the prey’s shell, similar to using a clam knife to open a clam.  It then inserts its long proboscis (tubular mouth part) to eat the soft flesh of its prey. Another feeding strategy is to use chemical secretions from its proboscis to drill a hole in the shell of its prey to reach the soft flesh.

 

Uncover Other Inhabitants

UNKNOWN

There is limited data available to quantify Wetland and Riparian Buffer Preservation, or updated data to quantify Wetland Acreage. The BBP has obtained funding and will begin assessment efforts for both targets, in the next few years.

 

 Hard Clam abundance has not been updated since 2012. Recovery of the stock will be guided by the Fishery Management Plan for Hard Clams, which is under development with the NJDEP, BBP, and other organizations. Reclam the Bay and other partners have continued to plant clams for restoration purposes. Continued plantings in strategic locations which maximize survival and reproduction is one strategy to pursue in the coming years. This work can use a model developed by Rutgers with BBP funding which identified areas where planted clams could have the greatest dispersal of their larvae and thus potentially maximally contribute to the recovery of the stock.

 Water Withdrawals were over the target in the 2021 report; USGS has not yet completed its latest update, so a definitive determination of status is not available. However, additional NJDEP data show that it is likely that we continue to not meet the target. Per capita water use has gone down, demonstrating the effectiveness of water-saving appliances and practices, but that decrease has been offset by population gains. 


IN PROGRESS

New maps quantifying Submerged Aquatic Vegetation extent were developed, but poor image clarity resulted in a high degree of uncertainty in the total acreage. NJDEP and Rutgers are working to resolve the uncertainty of these maps, and improve the total acreage estimate. Funding has also been obtained for further research and restoration activities. Several groups are developing potential restoration actions.

The USGS has completed the first phase of its study to identify minimum ecological flows in select Barnegat Bay tributaries. USGS scientists compared streamflow statistics between historical and current time periods to better understand trends in watershed flow conditions. This work provides a foundation for developing ecological flow targets in the Barnegat Bay watershed.  Similar to SAV extent, funding (approximately $450K) has been obtained by the BBP to complete the remaining phases necessary for threshold determination.

TARGETS ACHIEVED

No targets can be considered “Achieved” at this time.

 

NOT ACHIEVING

Several Public Swimming Beaches exceeded their safe swimming standards more frequently than during their baseline time period (2016-2018).

While most beaches are routinely safe for swimming, several problematic areas such as Beachwood, Hancock, Windward, and several lake beaches need track-down studies and restoration to pinpoint and address sources of bacteria.

Acres of Approved Shellfish Waters decreased from the last report. While this decrease was small, it represents a loss of previously approved waters. Similar to public beaches, track-down studies and restoration work are needed to pinpoint and address sources of bacteria.

 

Knobbed Whelk

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Knobbed Whelk
Photo credit: Joshua Davis on Flickr