Penaeus aztecus -

Penaeus aztecus naturally occurs in the northwestern Atlantic Ocean, ranging from Massachusetts (USA) to Yucatan (Mexico) ^[2,3].

First observation in Belgium

In the fall of 2018, an immature female shrimp from the family Penaeidae was caught during an anchor seine catch in the brackish water zone of the Scheldt near Antwerp. This specimen was tentatively identified as Penaeus aztecus ^[4].
 

Distribution in Belgium
    
With the exception of this single observation in 2018, the species has not been officially reported again on Belgian territory. Given the intensive (fish) monitoring on the Scheldt, this could indicate a rather accidental occurrence.
 

Distribution in neighbouring countries

The first official observation in the Mediterranean region took place in 2009 (Gulf of Antalya, Turkey) ^[5]. In the following years, the species rapidly spread across the coastal areas of the entire Mediterranean region ^[6-9]. In 2017, this shrimp was also found in the Black Sea, along the northern coast of Turkey ^[8]. Outside the Mediterranean and Black Sea regions, Penaeus aztecus has not yet been reported in Europe, aside from the single Belgian observation.

Multiple anthropogenic vectors could be responsible for the introduction of Penaeus aztecus outside its natural range. Since the species is often farmed in aquaculture facilities, escape is a potential vector, which may also explain observations near fish and shellfish farms ^[6]. Other possible introduction methods include transport via ballast water from ships ^[7] and illegal/intentional introduction ^[4,6]. Further secondary spread, in addition to the aforementioned pathways, could also be facilitated by the natural transport of eggs and larvae, hitchhiking on surface water currents ^[8,10]. In the future, genetic studies may provide more clarity on the colonisation history of Penaeus aztecus outside its natural range ^[11].

Based on a single observation in the Scheldt near Antwerp, it cannot be concluded that the species has established a presence in Belgium, let alone that it is successful in our region. It is likely that the species cannot yet establish permanent populations in Belgium.

The species occurs in both cold and warm temperate waters ^[3], with water temperatures ranging between 13.7 and 36°C ^[12-14]. The fastest growth appears to occur at water temperatures around 26°C ^[12]. Laboratory studies show that Penaeus aztecus burrows when the water temperature drops below the 12-17°C range ^[15]. Additionally, the species tolerates a wide range of salinities, from brackish to marine, although optimal growth seems to occur at lower salinities (8.5-17.0 psu) ^[12]. Juvenile individuals are typically found in estuaries or lagoons, while adults migrate seawards ^[16].

The introduction of Penaeus aztecus may potentially impact native biodiversity (and related economic activities) through competition with native shrimp species that share the same niche ^[8], as well as through the co-introduction of pathogens and parasites ^[17].

Apart from biological monitoring, no concrete measures have been identified to control this species.

So far, Penaeus aztecus is the only penaeid species in Belgium/North Sea. This family is distinguished from other shrimp species by the fact that the second pleura of the abdomen overlaps only with the third, not the first, and the first three pairs of pereopods are chelate.

The morphological features of the species include a smooth carapace (cephalothorax), a rostrum with 10 dorsal teeth and 2 ventral teeth. There is an adrostral sulcus (groove) and adrostral carina (ridge) that extend nearly to the posterior edge of the cephalothorax. A sulcus is present on the 6th abdominal segment, and the telson lacks spines ^[4]. Depending on the study, captured specimens of Penaeus aztecus vary greatly in length, ranging from 105 to 317 mm ^{[6,8,9,10,16]}.

The species is typically found in estuaries and coastal waters, with the highest concentrations observed on muddy bottoms at depths of less than 50 meters ^[3,16], although Penaeus aztecus has also been found at depths of up to 165 meters ^[10,18]. Adult individuals are generally active at night and burrow during the day ^[19,20]. Nighttime activity is influenced by light intensity and salinity, with activity increasing with higher salinity and decreasing light intensity, and vice versa ^[21].

[1]          World Register of Marine Species (WoRMS) (2024). Penaeus aztecus Ives, 1891. https://www.marinespecies.org/aphia.php?p=taxdetails&id=395176 (2024-10-18). 

[2]          Pérez Farfante, I. (1969). Western Atlantic shrimps of the genus Penaeus. Fish. Bull. 67(3): 461-591. [https://www.vliz.be/en/imis?module=ref&refid=391077] 

[3]          Williams, A.B. (1984). Shrimps, lobsters, and crabs of the Atlantic coast of the eastern United States, Maine to Florida. Smithsonian Institution Press: Washington D.C.ISBN 0-87474-960-3. xviii, 550 pp. [https://www.vliz.be/nl/imis?module=ref&refid=128467] 

[4]          Soors, J.; Breine, J.; D’Udekem d’Acoz, C.; Van den Bergh, E.; Van de Meutter, F.; Terrie, T. (2020). Penaeus aztecus Ives, 1891 (Crustacea, Decapoda), in the Scheldt estuary (Belgium): Isolated record or forerunner of a penaeid invasion? J. Exp. Mar. Biol. Ecol. 530-531: 151437. [https://www.vliz.be/en/imis?module=ref&refid=327554] 

[5]          Deval, M.C.; Kaya, Y.; Güven, O.; Gokoglu, M.; Froglia, C. (2010). An unexpected find of the western Atlantic shrimp, Farfante Penaeus aztecus (Ives, 1891) (Decapoda, Penaeidae) in Antalya Bay, eastern Mediterranean Sea. Crustaceana 83(12): 1531-1537. [https://www.vliz.be/nl/imis?module=ref&refid=244069] 

[6]          Zava, B.; Insacco, G.; Galil, B. (2018). The first record of the brown shrimp Penaeus aztecus Ives, 1891 in the central Adriatic coast of Italy. Bioinvasions Records 7(3): 293-296. [https://www.vliz.be/nl/catalogus?module=ref&refid=354271]

[7]          Ozcan, T.; Ates, A.S.; Özcan, G. (2019). The distribution of the alien species Penaeus aztecus Ives, 1891 (Decapoda, Penaeidae) in the Mediterranean Sea. Transylv. Rev. Syst. Ecol. Res. 21(2): 41-48. [https://www.vliz.be/en/imis?module=ref&refid=381339] 

[8]          Gönülal, O.; Türetken, P. (2019). One of the most invasive alien species, Penaeus aztecus Ives, 1891 reached the Black Sea coasts. Bioinvasions Records 8(4): 871-875. [https://www.vliz.be/en/imis?module=ref&refid=381250] 

[9]          Santos-Bethencourt, R.; Rotllant, G.; Abelló, P. (2023). The brown shrimp, Penaeus aztecus Ives, 1891, reaches the Iberian Peninsula Mediterranean coasts. Bioinvasions Records 12(4): 1015-1023. [https://www.vliz.be/en/imis?module=ref&refid=381249] 

[10]        Scannella, D.; Falsone, F.; Geraci, M.; Froglia, C.; Fiorentino, F.; Giusto, G.; Zava, B.; Insacco, G.; Colloca, F. (2017). First report of Northern brown shrimp Penaeus aztecus Ives, 1891 in Strait of Sicily. Bioinvasions Records 6(1): 67-72. [https://www.vliz.be/nl/catalogus?module=ref&refid=354245]

[11]        Darling, J.A.; Galil, B.S.; Carvalho, G.R.; Rius, M.; Viard, F.; Piraino, S. (2017). Recommendations for developing and applying genetic tools to assess and manage biological invasions in marine ecosystems. Mar. Policy 85: 54-64. [https://www.vliz.be/en/imis?module=ref&refid=381248] 

[12]        Venkataramiah, A.; Lakshmi, G.J.; Gunter, G. (1976). A review of the effects of some environmental and nutritional factors on brown shrimp, Penaeus aztecus Ives in laboratory cultures, in: Persoone, G. et al. (Ed.) Proceedings of the 10th European Symposium on Marine Biology, Ostend, Belgium, Sept. 17-23, 1975: 1. Research in mariculture at laboratory- and pilot scale. pp. 523-547 [https://www.vliz.be/en/imis?module=ref&refid=4837]

[13]        Wiesepape, L.M.; Aldrich, D.V. (1970). Effects of temperature and salinity on thermal death in postlarval brown shrimp, Penaeus aztecus. Texas A & M University: United States. x, 70 pp. [https://www.vliz.be/en/imis?module=ref&refid=391078] 

[14]        Lunz, G.R. (1956). Harvest from an experimental one-acre salt-water pond at Bears Bluff Laboratories, South Carolina. Prog. Fish-Cult. 18(2): 92-94. [https://www.vliz.be/en/imis?module=ref&refid=391079] 

[15]        Zein-Eldin, Z.P.; Aldrich, D.V. (1965). Growth and survival of postlarval Penaeus aztecus under controlled conditions of temperature and salinity. Biol. Bull. 129(1): 199-216. [https://www.vliz.be/en/imis?module=ref&refid=381341] 

[16]        Cruscanti, M.; Innocenti, G.; Alvarado Bremer, J.; Galil, B.S. (2015). First report of the brown shrimp Penaeus aztecus Ives, 1891 (Crustacea, Decapoda, Penaeidae) in the Tyrrhenian Sea. Marine Biodiversity Records 8: e81. [https://www.vliz.be//en/imis?refid=354114]  

[17]        Galil, B.S.; Innocenti, G.; Douek, J.; Paz, G.; Rinkevich, B. (2017). Foul play? On the rapid spread of the brown shrimp Penaeus aztecus Ives, 1891 (Crustacea, Decapoda, Penaeidae) in the Mediterranean, with new records from the Gulf of Lion and the southern Levant. Mar. Biodiv. 47(3): 979-985. [https://www.vliz.be/nl/catalogus?module=ref&refid=354277]  

[18]        Karachle, P.; Corsini-Foka, M.; Crocetta, F.; Dulcic, J.; Dzhembekova, N.; Galanidi, M.; Ivanova, P.; Shenkar, N.; Skolka, M.; Stefanova, E.; Stefanova, K.; Surugiu, V.; Uysal, I.; Verlaque, M.; Zenetos, A. (2017). Setting-up a billboard of marine invasive species in the ESENIAS area: current situation and future expectancies. Acta Adriat. 58(3): 429-458. [https://www.vliz.be/nl/imis?module=ref&refid=294111]

[19]        Holthuis, L.B. (1980). FAO species catalogue: Vol. 1. Shrimps and prawns of the world. An annotated catalogue of species of interest to fisheries. Digital edition. FAO Fisheries Synopsis, 125(1). FAO: Rome. ISBN 92-5-100896-5. xvii, 271 pp. [https://www.vliz.be/nl/imis?module=ref&refid=142556] 

[20]        Tavares, M. (2002). Shrimps, in: Carpenter, K.E. (Ed.) The living marine resources of the Western Central Atlantic. Volume 1: Introduction, molluscs, crustaceans, hagfishes, sharks, batoid fishes and chimaeras. FAO Species Identification Guide for Fishery Purposes, : pp. 251-291. [https://www.vliz.be/en/imis?module=ref&refid=391082] 

[21]        Matthews, T.R.; Schroeder, W.W.; Stearns, D.E. (1991). Endogenous rhythm, light and salinity effects on postlarval brown shrimp Penaeus aztecus Ives recruitment to estuaries. J. Exp. Mar. Biol. Ecol. 154(2): 177-189. [https://www.vliz.be/nl/catalogus?module=ref&refid=354279] 

VLIZ Alien Species Consortium (2024). Penaeus aztecus. Introduced alien species of the Belgian part of the North Sea and adjacent estuaries anno 2024. Flanders Marine Institute (VLIZ). 5 pp.